on the broadcast here tonight, raging river. the mississippi cresting near record highs now in memphis. and down river, they're watching the levees and preparing for the worst. the opposition. president obama on the road again. and tonight we're looking at the other guys. who are the republicans who want his job? the split. the surprising announcement from california, where that state's former first couple has come apart. and making a difference for those who've been left out in the cold and can't help themselves when a great american city falls on hard times. themselves when a great american city falls on hard times. "nightly news" begins now. captions paid for by nbc-universal television

good evening. one local official in tennessee called it a whole mess of water. that's exactly what it is. this is historic flooding, surging down the mississippi now. and it bears repeating. the water is flowing at the rate of 2 million cubic feet per second. the raging river flowing through eight states, three of them hardest hit. that includes tributaries and creeks that run off the mississippi. they're trying to manage and contain the water, in some cases using what was built after the last big one, the 1927 flood, when hundreds of people died in the south. and they're working hundreds of miles in advance, where the river is cresting because there's so much water behind it moving down river. we have two reports tonight. we begin our coverage again tonight in memphis, and nbc's janet shamlian. janet, good evening. >> reporter: brian, good evening to you. the mississippi crested here just below 48 feet. officially the second worst flood in the city's history. it's now filled with all kinds

of garbage and mud. and officials say it could be the end of the month before it completely recedes. the bloated mississippi crested in memphis just short of a record, but not without punishing low-lying areas, submerging homes between coffee-colored floodwater littered with debris. >> sometime next week we should start to see significant falling in the range of maybe a foot a day or more. >> reporter: but until then a watery week ahead for places like this school, which was high and dry a few days ago. a 3-foot-high, 90-foot-long retaining wall of sandbags was simply outmatched by the mighty mississippi. as the teachers started repairs on the ground floor, upstairs classes went on as planned. >> i felt like we were spared. i feel like we were prepared, we made the right moves. and just a lot of prayers were answered, too. >> reporter: in some respects it's a tale of two cities in memphis. iconic landmarks like graceland, the lorraine motel, and the blues clubs on beale street are

untouched. yet several hundred homes are likely a total loss beneath this muddy soup, leaving dozens of families homeless. maria belanos, a few weeks from giving birth to her fourth child. she and her children are staying in a shelter. it's not where she wants to bring a newborn. she told me, "i don't know what i'm going to do." as the river moves south, mississippi and louisiana are in its crosshairs. >> we're at the head of the delta. it's those folks down below, you know, is will the levee hold? >> reporter: a flood-weary memphis is relieved the worst for them at least is over. janet shamlian, nbc news, memphis. >> reporter: this is anne thompson. 40 miles south of memphis the mississippi is swallowing up the homes and casinos of tunica, washing out much of this mississippi river town and heading south. dump trucks and bulldozers are the heavy artillery in today's battle for vicksburg, as crews add six inches of dirt to the backwater levee, where the mississippi has pushed into the

swollen yazoo river and is climbing. how fast is this water rising? >> on the gauge the average here has been about a foot a day. >> reporter: today in vicksburg the river is moving at 1.8 million cubic feet a second, so fast it could fill louisiana's superdome in just 30 seconds. and it's expected to rise another five feet before crest next week. that means the river will run over this levee. so crews are reinforcing it with five miles of black plastic sheeting. >> it will protect the land from being washed away. it will shed the water off without it eroding the soil behind it. >> reporter: there are more than 2,000 miles of levee systems along the mississippi. the most common are earthen levees and flood walls. the earthen levees are made of clay, sand, or soil and can be up to 100 feet wide and up to 30 feet tall. other parts of the river are protected by flood walls, most commonly made of concrete, stone, or brick. >> it's the third largest watershed in the world. >> reporter: major general michael walsh, the man in charge of the system, says it's under

historic pressure. >> it's really stressing all of the flood walls and the levees, and so there's an immense amount of stress on all of those systems. >> reporter: today engineers looked for weak spots and signs of water burrowing under the levees. at headquarters general walsh continued to follow the plan that uses neighboring fields and farms as release valves for the mighty mississippi. >> the system's working as designed, but it's at the very edge of its design strength. >> reporter: here where the mississippi meets the yazoo the river is expected to surpass the great flood of 1927 by more than a foot. last week there was a road behind me. tonight it's part of the river. brian? >> anne thompson, along with janet shamlian, our team covering this flood tonight. both of you, thank you very much. now we turn overseas to pakistan, where there's more to report about osama bin laden's

three wives who were living with him at the compound when he was killed. as we reported here last night, the pakistanis have agreed to give the u.s. access to them, and now that we know more about that and about the women. nbc's peter alexander is in islamabad tonight. peter, good evening. >> reporter: brian, good evening to you. tonight nbc news has learned that u.s. intelligence officials expect pakistan to turn over osama bin laden's three widows for questioning. those women are presently being held in rawalpindi. that's just outside of islamabad. a pakistani military official tells us the u.s. must wait until pakistan has completed its own interrogations first. among the wives, bin laden's youngest, the 29-year-old amal, is said to be his favorite. she's strongly committed to his ideology. she's also still recovering after being shot by navy s.e.a.l.s during last week's raid. and this evening users on top al qaeda websites are threatening "serious consequences" if the pakistani government gives the

u.s. access to the widows or if the u.s. tries to bring the women back to the united states. nbc news has also learned that the u.s. has already shared threat information from materials seized in the compound with several other countries. brian? >> all right. peter alexander, our coverage from islamabad tonight. peter, thanks. now to the other front overseas. libya, which is back in the news tonight. the fiercest nato air strikes in several weeks bombarded tripoli today, pounding away at targets in the city of misrata, where the rebels are again claiming they're getting the upper hand in the fighting against gadhafi's forces. speaking of home, we haven't seen gadhafi in a while. our chief foreign correspondent richard engel bringing us up to date from benghazi tonight. richard, good evening. >> reporter: good evening, brian. u.s. officials say that gadhafi is increasingly isolated. rebels suggest that he's hiding

out in bunkers underneath his palaces in tripoli. but there are no signs that the libyan leader is willing to leave the country. nato seems to have awakened to what was becoming a forgotten war, launching a series of air strikes, including its most intense in weeks in tripoli. it targeted a military building and gadhafi's compound. gadhafi seems to have gone into hiding. he hasn't been in public since the last big nato air strike on his compound, nearly two weeks ago. nato insists it's not trying to kill the libyan leader. >> we have no evidence about what's mr. gadhafi's doing right now, and i tell you the truth, we're not really interested in what he's doing. >> reporter: u.s. officials believe gadhafi is still alive. rebel commanders say their plan is to launch a simultaneous assault from multiple fronts, now that nato support has increased. there are now at least three front lines. in the east rebel fighters are closing in on the city of brega. in the west by tunisia rebels have opened another front around zintan. misrata remains the most active

front. cut off except for its port. aid ships rushed by people frantic to leave. rebel leaders say gadhafi's security forces are starting to defect. >> if we intensify it for now, i think we'll see more defection and probably we're seeing the beginning of the end. >> reporter: but waiting for gadhafi to fall means desperation for refugees. thousands are willing to risk death to reach two tiny italian islands. u.n. officials believe more than 1,000 refugees have been lost at sea trying to leave libya so far. there are also reports, brian, that gadhafi's troops are forcing some of those refugees out of the country, herding them onto those overcrowded ships. nato says those reports are disturbing. brian? >> unbelievable story just unfolding there every day. richard engel in benghazi, libya for us tonight. richard, thanks. let's turn now to politics in this country. and the question to the republican field, who wants the job of president?

yes, it's early yet, but consider politics and our recent history. at this stage of the game there are usually a lot more big names already in the race. our chief white house correspondent, chuck todd, with us tonight with more on this story. chuck, good evening. >> reporter: good evening, brian. so much for this idea that presidential elections are neverending campaigns. the summer is approaching, and the republican field is still taking shape. one of the few announced candidates for president was out campaigning and raising money today. >> wonderful to be back with all of you in the lone star state. >> reporter: but despite a sputtering economy and the incumbent's tepid job ratings, republicans aren't stampeding to join the president on the trail. take mitt romney, the candidate many view as the front-runner for 2012. by this time four years ago romney had not only officially announced, he was running tv ads and participating in debates. >> the conventional wisdom is you can never get in early enough. last year we proved you get in too early you waste millions of dollars you desperately need

later. >> reporter: this time around romney says he's "still exploring." he skipped the first debate last week, leaving minnesota governor tim pawlenty as the only major contender alongside a slew of long shots jockeying for attention. >> governor johnson, if you had a reality tv show like donald trump does -- >> i don't think it would be donald trump's show. i don't think it would be sarah palin's show, either. >> how many people here would use heroin if it was legal? i bet nobody would put their hand up. oh, yeah, i need the government to take care of me. i don't want to use heroin, so i need these -- >> most of the candidates in the debate aren't even beyond the margin of error in a poll. you can't prove they exist. it was not a very serious debate. >> reporter: but with the clock ticking and president obama raking in millions, some on the fence are making decisions. former house speaker newt gingrich makes it official tomorrow and is trying to confront his past marital problems by making his third wife, calista, a centerpiece of

his campaign. and president obama's one-time ambassador to china, john huntsman, is inching closer, last week giving a commencement address in south carolina. but speaker john boehner is among a group of influential republicans pushing for more choices, like new jersey's chris christie. >> i think he's done a great job. and he speaks english like in plain talk. >> reporter: and indiana governor mitch daniels. >> another person who's got a real track record of reform in his state, the kind of reforms that we need to have in washington, d.c. >> reporter: brian, gingrich will announce on twitter and facebook, and thursday mitt romney will use powerpoint to try and distance himself and the massachusetts health care reform plan he signed into law from obama's. and a quick correction from last night. james knox polk in fact was a house speaker who did become president. gingrich, if successful, would only be the second and the first speaker in 100 years to run, brian. >> oh, we heard from a lot of history majors last night. >> reporter: yes, we did. >> chuck todd in our d.c. newsroom. chuck, thanks.

in the state of texas tonight a bill that would require colleges to let students carry concealed weapons on campus is a step closer to reality. the state senate passed the bill over the objections of some lawmakers and college officials, who as of now can make their own rules regulating guns in campus classrooms. the bill still needs to pass the state house of representatives but is expected to have enough votes to pass there too. when we come back here tonight, the news from california that the unlikely pairing that became a long-time union is now apparently no more. and later, a city struggling with hard times and how the effort to help the best friends left behind is making a big difference there.

it was the news that broke overnight, and it had a say it ain't so aspect to it. the "l.a. times" report that maria shriver, a member of the kennedy family, long-time nbc family member, and her husband, former california governor

arnold schwarzenegger, have split after 25 years of marriage and four children together. and with the reaction the search for any recent signs that it was coming. our report tonight from nbc's kate snow. >> reporter: they were one of america's best-known couples. a journalist daughter of the kennedy clan who endorsed obama. >> i'll be back. >> reporter: and the actor turned cigar-smoking republican governor. in 2009 he joked about the secret to his success. >> number one, come to america. number two, work your butt off. and number three, marry a kennedy. but anyway. >> reporter: they married 25 years ago on cape cod, have four children, an estate in brentwood. but look more closely, and perhaps there were clues of cracks in that perfect facade. at a women's conference she created shriver said the passage of time means different things to different people. >> for some it's time to get married. for others time to leave a relationship that just doesn't

work anymore. >> reporter: this past weekend at their nephew's graduation shriver was not wearing a wedding ring. in a joint statement the couple talked of a time of great "personal and professional transition" since schwarzenegger left office. "we came to this decision together," they said. shriver has admitted she didn't want her husband to run for governor, but she supported him, even in the face of allegations of sexual harassment. and over time she became a pioneering first lady. >> she was a kennedy. that gave him legitimacy as a politician. >> reporter: the family has been through a tough period, losing shriver's father, mother, and uncle in a short span. schwarzenegger plans to make more films. but shriver has seemed to struggle with what's next. in march she asked for advice on youtube. >> it's so stressful to not know what you're doing next, when people ask you what are you doing and then they can't believe that you don't know what you're doing. >> reporter: today as the

paparazzi grabbed shots of the former governor, many offered support and prayers for a glamorous couple facing all too common troubles. kate snow, nbc news, new york. up next here tonight, the wild show that broke out while a big crowd was watching something else.

this was the scene this past weekend in colorado as a

helicopter hovering low taking pictures of a skateboard race lost its rotor speed and then dove down to the ground. the pilot managed a hard landing just feet from where the crowd was watching the race. a nice save in a way, but way too close for comfort. no one was hurt. they're looking into how and why it happened. looks like two big names are coming together. microsoft and skype combining the established web company with the live telecommunications service that has really revolutionized keeping in touch, considering the fact that picture phones were science fiction just 20 years ago. the proposed skype selling price, about $8.5 billion, give or take, making it microsoft's largest acquisition ever. we lost a member of our family here today, and it's important that you know about our friend jeff gralnick because for over 50 years he's been behind so much of what you've seen on television on this network and on three others. jeff gralnick started on tv at

cbs news in 1959. while he was a producer by trade, american viewers also saw his work when he reported on air from vietnam. the tet offensive and khe sanh. he was later among the first producers at "60 minutes." from there it was on to abc news and nbc news and cnn. he worked with all of them. cronkite, kuralt, brinkley, jennings, reasoner, walters, brokaw, and yours truly starting in '93. jeff brought abc's newscast from third to first. then he came over here and did the very same thing when tom brokaw was in this chair. jeff loved politics, went to work for george mcgovern briefly, but the pull of covering space shots, conventions, elections, wars, and revolutions just proved too much, so he went right back to the news business. he was at my side on election nights and most recently was a special consultant to our news division president steve capus. we found a quote from jeff today which is kind of perfect.

"always demand what is right and never accept second best." jeff gralnick was a fixer, a teacher, a taskmaster, a leader, a husband, a parent, and a friend. he was 72 years old. we'll be back in a moment with tonight's "making a difference" report.

finally tonight, with the economy in the tank lately, few cities have had it worse than detroit. the proud motor city where the population is actually shrinking with entire neighborhoods left abandoned. it's hard enough for the people left there to fend for themselves, but what about those they leave behind with no voice of their own? now some folks are trying to change that and making a difference in the motor city. our report from nbc's kevin tibbles. >> reporter: it's a hard and dangerous existence for man's best friend in the motor city. keeping an eye out for strays is dan carlisle, a local rap artist who goes by the name of hush. >> this is the streets of detroit, man.

you know? it's rough out here. i mean, it's rough out here for citizens. >> reporter: while the people population of detroit has plummeted from 2 million in the 1950s to just 700,000 today, the stray dog population has skyrocketed. >> you see these poor creatures that don't have a voice of their own and no one to help them. >> reporter: when times get tough and families flee, the pet is often left behind. today in detroit there are an estimated 50,000 stray dogs on the street. >> it makes me mad. and you know, it makes you sad. >> what's your 20 now? >> reporter: hush grew up on these streets. >> whatever came this way? >> oh. >> reporter: and by starting the detroit dog rescue, he and his crew work to give strays a second chance. >> yeah. he's going to be fine. >> reporter: with almost military precision, volunteers patrol where dogs occupy abandoned homes and scrounge in packs for survival. always hungry, often sick and frightened. >> when i look at a dog's face and i just -- i look in its

eyes, i feel something. i need to do something. i can't walk away. >> reporter: the city of detroit's animal control says it euthanizes 81% of dogs because its shelters are full. detroit dog rescue seeks to find the dogs new homes and wants to build a no-kill shelter. so far this year dozens have been spared. and when there is an owner -- >> you've got to find a way -- >> reporter: -- they're politely asked to spay or neuter. >> when a dog comes up to me and he puts his head down and he just rolls over and just submits to you, it's like please, like you know -- >> reporter: help. >> help. >> reporter: in a city struggling to put itself right, hush says some of the most vulnerable inhabitants should never be left alone to fend for themselves. kevin tibbles, nbc news, detroit. >> tough to watch. but you've got to have hope. that is our broadcast for this tuesday night. thank you for being here with us. i'm brian williams. we hope to see you right back here tomorrow evening. we hope to see you right back here tomorrow evening. good night. -- captions by vitac -- www.vitac.com

right now at 6:00, emotions running high in san bruno as the neighborhood devastated bit pipeline explosion marks a major milestone. these teachers are showing the work doesn't stop with the last bell rings. a bay area grade to show opposition to state budget cuts. telling his story. the man hailed a hero on the in-flight disturbance speaks to nbc bay area. the news at 6:00 starts right now.