this is "nightline." >> tonight, president obama making the case for a president hillary clinton. >> she is fit and she is ready to be the next commander in chief. >> his strong words against donald trump. >> america isn't about yes, he will. it's about yes, we can. >> the republican candidate stirring the pot. >> russia, if you're listening -- >> plus the long and winding road to this pivotal moment in history for an unlikely team of rivals. >> well, that hurts my feelings. >> you're likeable enough. >> cut-throat competitors to trusted friends. and those memorable convention words from the first lady here the other night. >> i wake up every morning in a house that was built by slaves.

>> sparking comments from fox tv's bill o'reilly that those slaves were well-fed, setting up a 21st century tweet storm over a bitter chapter in american history. first the "nightline 5." >> a lifetime of your dog's nutritional needs all in one. purina one. healthy energy and a taste he loves. purina one smart blend is expertly blended with always real meat number one. all in one, purina one. hey, need fast heartburn relief? try cool mint zantac. it releases a cooling sensation in your mouth and throat. nexium can take 24 hours. try cool mint zantac. no pill relieves heartburn faster. >> number one in just 60

good evening from philadelphia. thank you for joining us. the passing of the baton, that moment, that embrace, many here may never forget. hillary clinton joining the president on that stage after his passionate speech on why she should be the one to succeed him. tonight president obama may have saved his best line for last. and he never said a word. >> to elect hillary clinton as the next president of the united states. >> reporter: the arena erupted when president obama left the podium and brought back his friend. if history had a scrapbook, tonight we in the world saw its newest addition. a monumental handoff. the first black president passing the torch who the democratic party hopes will be the first female president. >> there is only one candidate in this race who believes in that future. a leader with real plans to break down barriers. and blast through glass ceilings. and widen the circle of opportunity to every single

american. the next president of the united states, hillary clinton! >> reporter: in what's been described as the biggest moment president obama has left the national stage, focusing not only on the accomplishes of his presidency but the promise of a clinton administration. >> no matter how daunting the odds, no matter how much people tried to knock her down, she never, ever quits. >> reporter: the president more popular than either of the candidates running to succeed him wasted no time in going after clinton's opponent and his possible successor. >> does anyone really believe that a guy who spent his 70 years on this earth showing no regard for working people is suddenly going to be your champion? your voice? hey, if so, you should vote for him. >> reporter: this morning trump inserted himself into the big controversy looming over the democratic national convention this week. the release of nearly 20,000 dnc

e-mails by wikileaks. e-mails that showed the dnc was trying to undermine the sanders campaign. the clinton campaign pointing fingers at russia saying the e-mails were leaked to help the trump campaign. >> it's just a total deflection. this whole thing with russia. >> reporter: trump essentially encouraged russia to conduct espionage against his opponent. >> russia, if you're listening, i hope you're able to find the 30,000 e-mails that are missing. i think you will probably be rewarded mightily by our press. >> do you have any qualms about asking a foreign government -- russia, china, anybody -- to interfere, to hack into a system of anybody's in this country -- >> that's up to the president, let the president talk to them. >> does that not give you pause? >> no, gives me no pause. >> reporter: the bipartisan backlash fast and furious. clinton's top foreign policy adviser calling this a national security issue adding, this has to be the first time that a major presidential candidate has

actively encouraged a foreign power to conduct espionage against his political opponent. from a spokesman for house speaker paul ryan, russia is a global menace led by a devious thug. putin should stay out of this election. trump seeing it a different way. >> i'm not going to do putin what to do, why should i tell putin what to do? >> what do you make of what donald trump said? >> we've gotten used to outrageous comments, appropriateness is defined so far down of what we think a presidential candidate should speak like. it seems to be another example, a blog block, is this man fit to hold presidential office? >> reporter: tonight vice president joe biden went after trump hash. >> his lack of empathy and compassion can be summed up in a phrase i suspect he's most proud of having made famous, "you're fired." how can there be pleasure in saying "you're fired"? he's trying to tell us he cares

about the middle class? give me a break. that's a bunch of malarkey. >> reporter: then in an attempt to attract republican and independent voters across the country, former new york city mayor michael bloomberg. >> i'm a new yorker. and i know a con when i see one. >> reporter: to make the case that clinton is the best choice for swing voters. >> let's select a sane, competent person with international experience. a unifier who is mature enough to reach out for advice. >> reporter: then we ran into another group of democrats turned off by trump. >> hillary offers everything that donald trump cannot. >> reporter: only 4% of african-american voters support donald trump. while polls show clinton with 89% of african-american voters' support. new york representative gregory meeks is a member of the congressional black caucus. >> in the primary it was the black community that rallied a around and gave her a

substantial vote that put her over the top. it will be the black community, i believe, that will do that again in november. >> hello, fellow democrats! >> reporter: there were heartbreaking moments when the topic was gun violence. speakers like erika smelgowsky. her mother was the principal of the sandy hook elementary school, killed in the 2012 shooting. >> i'm here alone without my mother, while too many politicians cower behind the gun lobby instead of standing with american families. 91 people are murdered or commit suicide with a gun every single day. that's an insane number. if any other epidemic was plaguing our country like that, people would have acted by now. >> do you think your message would have resonated at the republican convention last week in cleveland? >> donald trump thinks he can walk down fifth avenue and shoot someone and not lose any votes, so no. >> america is already great.

america is already strong. >> reporter: president obama's now a veteran of the dnc stage. but 12 years ago to the day, he was just another fresh face. young senator from illinois who captivated conventiongoers with this message of unity. >> there is not a liberal america and a conservative america. there is the united states of america. i was filled with faith. faith in america. the generous, big-hearted, hopeful country that made my story, that made all of our stories, possible. >> reporter: in subsequent convention speeches, obama continued to preach these same themes of hope and unity. in 2008 -- >> and i will restore our moral standing so that america is once again that last, best hope for all who are called to the cause of freedom. >> reporter: and in 2012 -- >> ours is a future filled with hope.

and if you share that faith with me, if you share that hope with me, i ask you tonight for your vote. >> reporter: after his wife's successful speech on monday night, obama stayed up until 3:30 in the morning working on perfecting his own words. today he didn't seem the least bit nervous. >> democracy isn't a spectate are sport. america isn't about yes, he will. it's about yes, we can. >> reporter: also feeling great tonight, officially accepting his nomination as vice president today, virginia senator tim kaine took the stage with confidence. kaine has never lost an election. he is one of only 20 people to have served as a mayor, governor, and senator. >> god has created in our country a beautiful and rich tapestry, an incredible cultural diversity that succeeds when we embrace everybody in love and battle back against the forces,

the dark forces, of division. we're all neighbors. >> reporter: the minnesota native and father of three got his start as a civil rights lawyer. he took a year off from studying law at harvard to help run a small vocational school in honduras. it is there he learned not just a language but a culture. skills and sensibilities on display tonight. and the party hopes it will pay off in november. [ speaking spanish ] faith, family, and work. >> reporter: the dnc has been a star-studded affair. night three was no different. >> we will come together. >> reporter: actress sigourney weaver. angela basset. director lee daniels. tv personality star jones taking center stage. but even that star power paled when hillary clinton came out to thank barack obama. and next, first bitter rivals, now passing the torch. the remarkable evolution of team

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as the song goes, you and me got a whole lot of history. could be an anthem for the tumultuous relationship between president barack obama and his foe turned friend, now possible successor, hillary clinton. my "nightline" coanchor juju chang on their unique and evolving connection. >> reporter: tonight, it was the commander in chief passing the torch. >> the next president of the united states, hillary clinton!

>> reporter: throwing his weight behind hillary clinton. >> there has never been a man or a woman -- not me, not bill, nobody -- more qualified than hillary clinton to serve as president of the united states of america. >> reporter: powerful praise. seems hard to believe less than a decade ago these two were bitter rivals in a contentious primary. >> hillary, you just spoke for two minutes -- >> i did say anything about ronald reagan -- >> reporter: two senators painted as radical opposites, clinton the washington insider with long-standing ties to the political elite. >> yes, we can. >> reporter: obama, the wide-eyed dreamer with an easy smile. his lack of experience often the target of her thinly veiled contempt. >> with little national or international experience -- >> what they really mean is i haven't been in washington long enough. >> reporter: the then-junior senator from illinois turning her greatest strength into a weakness. >> senator clinton is claiming, basically, the entire eight

years of the clinton presidency as her own, except for the stuff that didn't work out. >> what can you say to the voters who seem to like barack obama more? >> well, that hurts my feelings. >> you're likeable enough, hillary, no doubt. >> thank you. >> reporter: but not likeable enough to win the nomination. she endorsed her opponent in that now-famous concession speech. >> so today i am standing with senator obama to say, yes, we can! >> reporter: but after a bruising defeat, a truce of sorts. in her book "hard choices," clinton describes a secret meeting with obama. lying down in the back seat of a car, hiding from the press. she spoke about it with diane sawyer. >> and you had chardonnay -- >> california chardonnay. it was like an awkward first date. obviously i had known him for several years but the campaign was so intense. and our staffs and our supporters were really at odds with each other. i don't think we ever felt that way about each other.

>> oh, yes, you did. >> no, not really, diane. >> reporter: the covert meeting launching a sea change in democratic politics and the obama/clinton era. >> i remember after the campaign when some of the bad blood was still there and i'd say something to hillary clinton, he'd say, get over it. >> reporter: david plouffe was president obama's campaign manager during that '08 run, later a senior advise tort president. >> give us a little bit of flavor of their relationship. >> it's become chummy, they tease each other. he talked to her a decent amount during this primary campaign. >> what do they tease each other about? >> well, you know. if a speech is too long or a mannerism -- there's just a comfort there. >> we must elect barack obama and joe biden on november 4th! >> reporter: clinton soon a weapon for unity, cutting short obama's convention roll call early in 2008 to nominate him by acclamation. >> barack obama is our candidate and he will be our president! >> reporter: as barack obama made history, clinton's star

continued to rise. >> mr. president-elect, thank you for this honor. >> reporter: obama wanted a team of rivals, naming her secretary of state. >> i remember the first time he told me he was thinking about picking her. i thought he was out of his mind. because i was still harboring some of the resentment. and body of them got over it very quickly. barack obama always knew hillary clinton had it. she'd be prepared, she'd be thorough, and that's what hadn'ted in a secretary of state. >> reporter: they spoke about the choice. >> despite our hard-fought primary, we had such agreement on what needed to be done for our country. >> it made for tough debates because we could never figure out what we differed on. >> reporter: in this position she would travel nearly 1 million miles and globe trot to a record 112 countries. her proudest moment with the president, that decision to go in and get osama bin laden. this photo taken while watching the raid in the situation room. >> my heart was in my throat

because we were watching on the video screen what was happening. and we saw one of the helicopters' tail clip the wall as it tried to get into the compound. >> you really didn't tell president clinton about osama bin laden? >> no. no, i mean, i take very seriously the obligations of secrecy. >> reporter: clinton stepped down as secretary of state after four years. but her tenure forever marred by the fallout from the 2012 benghazi attack. >> yesterday, four of these extraordinary americans were killed in an attack on our diplomatic post in benghazi. >> reporter: and her controversial decision to use a private e-mail server led to even more federal investigations. president obama defended her to "60 minutes" last year. >> i don't think it posed a national security problem, i think that it was a mistake that she's acknowledged. >> reporter: when she resigned from the state department, many believed she had her eyes set on the highest office once again.

now her old boss and former foe, who provided the launching pad for her second shot, tonight giving her an electrifying boost. ♪ signed sealed delivered i'm yours ♪ >> reporter: for "nightline," i'm juju chang in philadelphia, pennsylvania. up next, bill o'reilly backlash over his comments about slaves and the white house. with advil, you'll ask what muscle pain? what headache? what arthritis pain? what bad wrist? advil makes pain a distant memory nothing works faster stronger or longer than advil it's the world's #1 choice what pain? advil.

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finally tonight, the very vocal backlash against bill o'reilly for his comments about slaves. it all started with mrs. obama's poignant words about life at the white house. >> my daughters and all our sons and daughters now take for granted that a woman can be president of the united states. >> reporter: first lady michelle obama delivered a universally applauded speech on the first night of the democratic national convention. even including a mention of one of the darkest chapters in american history. >> i wake up every morning in a

house that was built by slaves. >> reporter: everyone was impressed with the first lady, even donald trump telling "the hollywood reporter," "i thought she did a very good job, i liked her speech." contrarian fox anchor bill o'reilly agreed with mrs. obama on the facts but then went further. >> slaves that worked there were well fed and had decent lodgings provided by the government -- >> reporter: o'reilly's comments sparking major backlash for making light of the treatment of slaves. >> i find it offensive when anyone tries to justify any part of slavery. >> reporter: shonda rhimes tweeting, try slavery, bill, let us know how good the food is while you wear chains. a picture of shackles with the caption, dear bill o'reilly, wear these. tonight o'reilly in full damage control. >> -- in order to keep slaves and free laborers strong, the washington administration provided meat, bread and other staples, decent lodging on the grounds of the new presidential building. that is a fact. not a justification, not a defense of slavery.

just a fact. anyone who implies a soft on slavery message is beneath contempt. >> reporter: it was republican president abraham lincoln who said, when i hear anyone argue for slavery, i feel a strong impulse to see it tried on him personally." thank you for watching abc news. tune in to "good morning america" tomorrow. as always we're online at abcnews.com and our facebook page. from philadelphia and the