tonight on "nightline" -- michigan mayhem. it may be mitt romney's turf. he won here four years ago. he lived here for months. but underdog rick santorum nearly stole the win in his opponent's home state tonight. what does it mean for republicans hoping to beat obama? stranded at sea. a cruise ship adrift without power, for two days in pirates-infested waters. passengers sleeping on the decks to avoid the searing decks below. we're near the seychelles. and sumatra's last tigers.

these ferocious cats are built to kill. but their lives are threatened by poachers. we get up close of these majestic beasts, living on the edge of extinction. good evening. i'm bill weir. that gust you heard earlier tonight, that was the sound of mitt romney, exhaling, after watching his momentum slam into rick santorum and then careen over a few of his own gaffes. romney did win primaries in both arizona and his home state of michigan tonight. but while he is a few dozen delegates closer to the nomination, the michigan could sting him in the fall if he gets that far. john berman explains how and why, in tonight's "your voice, your vote." michigan, it's the state where they make cars. but moore importantly, it's the

state shaped like a hand. and for the last two weeks, that hand had an unprecedented grip on the republican contest. with candidates traveling from pinky to forefinger, tryinging to get a thumbs up. let's talk to the hand. first, the ring finger. mitt romney loves michigan. >> thank you. >> and tonight, it loves him back. >> what a win. this is a big night. >> michigan is where his father was governor. and where, as a teenager, he met his wife. and apparently made out with her. >> i kissed her there. oh, yeah. she was 16. >> reporter: next up, the middle finger. we won't show you that. but mitt romney and rick santorum, repeatedly showed it to each other. mitt romney mocked rick

santorum's past senate votes. >> my team is the people of michigan and america. and i'm going to fight for you. >> reporter: rick santorum mocked mitt romney's convictions and that he is resolute. >> maybe he doesn't know what the term resolute means. it's supposed to be you have a resolve of a consistent patterns or beliefs. >> reporter: but for romney, the bigger problem might be the pinky. the kind that elitists raise when they drink their tea. it was during this fight in michigan, where this private equity giant, revealed what his wife drives. not one but -- >> ann drives a couple of cadillacs, actually. >> reporter: and when asked if he follows nascar -- >> not as much as some of the ardent fans. but i have friends that are nascar team owners. >> reporter: despite his impressive come from behind victory to lead number one, some

say mitt romney may be leaving with the mantle of being out of touch with common americans, the kind that romney will need in a general election. as for rick santorum, that hand is clearly a right hand. signifying a rightward shift in r rhetoric. >> i had a chance to read the speech. and i almost threw up. >> reporter: and for the president suggesting all kids should go to college. >> the president of the united states said that every child in america should go to school. what a snob. >> reporter: again, whether or not you agree with these statements or the subject matter in the gop contest, it appears to be turning off some independents. in an abc news poll out today, among independents, just 32% see santorum favorably. 29% romney. four years ago at this time, both barack obama and john mccain were at or above 50%

favorability, among the candidates. >> it will distance them all from independent voters they need to get in november. >> reporter: this has left some republicans wondering if another candidate should get in. >> they barely win his home state of michigan. and that puts them in a position where they know he's still vulnerable in the primary, but really vulnerable in the general election. >> thanks, you guys. you are the best. >> reporter: a win is a win. and for mitt romney, victory in michigan is sweet. but that applause from republicans you hear, might be feint, the sound of one hand clapping. i'm john berman, for "nightline," in new york. >> thank you, john. we'll get to the romney victory party. but let's start with jonathan karl with the santorum camp who would want to paint this loss as a win. when it comes to delicate count,

that's not just spin. >> reporter: it's not over yet. mitt romney has won in terms of the vote. but the delegates are awarded proportionally by delegate district. and if you were watching the speech, with santorum, you would never know he lost the popular vote here. he talked about this as a victory for him. i spoke with him just as he was leaving. said this is a huge win for us. we came into mitt romney's backyard and did as well as they did. they think the next round will be on their turf, not on romney's home turf. >> next round is a big turf. let's go to david muir and the romney camp. i'm a little disappointed that you're not at the romney party with surrogate kid rock, so we could see the governor mix in that crowd. how did the night unfold there?

>> reporter: governor romney, thanking the voters in michigan. those morning headlines could have been different come tomorrow. but tonight, he did eke out a win here in michigan. he said, we didn't win by a lot. but a win was a win. this is very important. this was his home state. and his advisers want to shift this conversation back to the economy, after a week or so of santorum and social issues. they said the only reason they survived here is because romney didn't climb into that rabbit hole dug by santorum on those issues. tuesday will be a big challenge, with many supporters who will still come out in force. and romney's been not able to break through with many of the groups. and in addition to the independents he needs, as well, that john berman pointed out. big challenges with super tuesday a week away. >> we should mention newt gingrich, ron paul, a distant third and fourth. but who knows in the gop race this year? they could come back next week.

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>> announcer: "nightline" continues from new york city, with bill weir. part of the appeal of a cruise vacation is a promise of all of the blue water between you and the daily grind. but the flipside, when a vacation goes south, it's really tough to leave. one fleet has driven this home in the past month. first, "the costa concordia," off italy. and now, "the costa allegra" is in waters frequented by somali pirates. jeffrey kofman is there. >> reporter: good morning to you. it is wednesday morning in the

indian ocean. it is hot and humid. but thankfully nothing more than that. for the second night in a row, more than 1,000 passengers and crew on that stricken cruise ship, had to sleep out on the decks, under the stars. that is the "costa allegra," crippled at sea, because the 636 passengers and 413 crew, have been stranded hundreds of miles from land, on a ship, with no electricity. no toilets. no air conditioning. no way to cook food. the ship, owned by miami-based carnival cruise line, even ran out of fuel for its emergency generator. for so many onboard, it was to be the vacation of a lifetime. it began in the indian ocean of mauritius. it made its way to madagascar on saturday. it was in open water on monday, heading to the seychelles, when suddenly, an emergency was

sounded. a fire below deck knocked out the ship's generators. no one was left injured. but the ship was left adrift off the most perilou waters on earth, where roams of pirates roam the seas, searching for ships to seize. >> this cruise ship, had armed guards to respond if they were attacked. >> reporter: the first boat to respond to the distress signal, a french fishing ship. it began towing the ship to safer waters, slowly. "the allegra" is now making its way here to port victoria, on the main island of the seychell seychelles. it was to go on to inam and then on. who says disaster can't strike twice. disaster has struck the costa

cruise line twice in one month. in the chaos that followed, thousands had to abandon the ship in darkness, while the captain and many crew abandoned them. all is too close to home for jane thomas, from birmingham, england. her son was on the "costa concordia." part of a human chain. and her daughter is working on "the costa allegra." jane just wants to get her daughter safely home. two children, working on two ill-fated ships, too much. >> all of the ships that are sailing in the ocean, and the two that my two have been on. >> reporter: as for james, he's thinking of another line of work. >> it's shame because i do love cruising. and i did want to go on another

one. then, looked on youtube at a picture of the ship. and went no. no chance. >> i think a lot of people are getting nervous about cruising. we know after the "costa concordia" disaster, bookings dropped in the double-digits. i would think twice about taking a costa cruise because two incidents so close to one another give me pause. >> reporter: cruising sells itself as a worry-free, hassle-free, dream vacation. but that's not always what it delivers. this was the scene in san diego harbor in 2010, when the crippled carnival "splendor," had to be pulled to port after a fire knocked out its generator. there were at least ten cruise ship fires in the previous three years, killing six onboard. so, at this critical time for the travel industry, when people are booking their summer vacations, is cruising safe?

>> if you look at it statistically, cruising remains one of the safest forms of travel. >> reporter: the now hobbled "costa allegra" is making its way to the main island of the seychelles chain. it's expected to arrive thursday morning local time. when it does, it's going to put strains on the resources here, as they search to find hotel rooms for all of the passengers and to find flights. a word of advice for those thinking of taking a cruise in the coming months or years. remember, to take a flashlight. bill? >> jeffrey kofman, our thanks to you. coming up next, what happens when one of nature's most fearsome predators starts hunting its human rivals? ah, claim trouble. [ dennis ] you should just switch to allstate, and get their new claim satisfaction guarantee. hey, he's right man. [ dennis ] only allstate puts their money where their mouth is. yup. [ dennis ] claim service so good, it's guaranteed. [ foreman ] so i can always count on them. unlike randy over there.

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for the tiger, stripes are

not fashion. they are functional. jungle camouflage. but what happens when the jungle starts to disappear around the tiger? and what happens when the killer cats start turning tooth and claw against their human neighbors? here's abc's stephanie sy. >> reporter: a maneater is on the loose in the forest of sumatra. eight people killed over just two months. the victims' bodies partially devoured. terror spreads on the small indonesian island. and the pressure to find the killer mounts. the sumatran tiger is one of the most aggressive big cats on the planet. and it's built to kill, with the largest teeth of any land-base ed predator. >> the only thing that stops us, is us. >> reporter: only 400 of these top carnivores remain in the

wild. their habitat has been decima decimated. >> they rely on the ability to hunt on a regular basis of their prey. tigers themselves are suffering because of lack of prey. >> reporter: as humans exploit the riches of the forest, it means more contact with hungry tigers. who maybe are starting to see men as their next meals. the rash of attacks have park rangers on the hunt for a man-eater. they set a trap and bait it with live prey. by dawn, they captured an aggressive adult tiger. but is she the man-killer? there's no physical proof. but the rangers take her away, nonetheless. in a cage, she becomes a zoo attraction. for most, it's the only way to see a live sumatran tiger, so rare have they become in the wild. conservationists worry they'll

go the way of the tigers in bali and java before them, extinct. >> tigers have gone over a massive decline. over 95% decline in their population over the last 100 years. >> reporter: illegal poaching is another reason for their decline. and in sumatra, accounts for 78% of tiger deaths. while some researchers believe captive breeding ensures the survival of the species, others say it detracts from saving tiger and human lives. >> it's a challenge but not a complex challenge. we need to secure areas that we allow tigers to live unharmed. so, basically, if you give them enough prey, give them enough space, tigers will not choose to hunt people. >> reporter: and that means protecting their home, the forest. for sama, the tiger that was caught and perhaps wrongly accused, captivity has led to weight gain and declining health. she moved to another facility that is supposed to prepare

captive-bred tigers for life in the wild. in a rare and controversial practice, they feed live prey to the tigers to keep their hunting skills sharp. try as they might, not a single tiger bred in captivity have survived after being released in the wild. >> they're not competitive animals anymore. when you're put back in the wild, other species will kill them. they will come into contact with people, which often ends badly for the tiger. >> reporter: the brutal attacks on people continue while salma is in captivity. and the death toll reaches a historic high, shocking even if scientists. but it also means that salma probably wasn't the killer after all. at least she's now safe from poachers. but for the dwindling population of this magnificent tiger, the future has never been more uncertain. for "nightline," i'm stephanie sy, in new york. >>