Charlotte, North Carolina - Former President Bill Clinton and President Obama hugged onstage Wednesday night after Mr. Clinton delivered an impassioned plea on behalf of Mr. Obama's re-election, the 42nd president nominating the 44th to a second term with a forceful and spirited argument that Democratic values would restore the promise of the middle class.
The former president delivered a point-by-point rebuttal of the arguments made during the Republican National Convention last week, warning against Republicans taking back the White House and declaring, "We can't let it happen."
He offered an equally detailed affirmative case for the re-election of Mr. Obama, saying there was no question the country was in a better position than it was four years ago.
"We simply cannot afford to give the reins of government to someone who will double down on trickle down," Mr. Clinton said, repeatedly bringing the crowd at the Democratic convention to its feet. He added, "I love our country so much and I know we're coming back."
Mr. Clinton drew sharp lines between the choices facing voters in November. He made the case in a deeply personal way, sometimes articulating the argument for Mr. Obama more forcefully than the president has done throughout his race with Mitt Romney.
"We believe 'we're all in this together' is a better philosophy than 'you're on your own,' " Mr. Clinton said.
The delegates at the Democratic convention conducted the ceremonial roll call vote after Mr. Clinton's speech, with Ohio putting Mr. Obama over the top and formally elevating him as the party's presidential nominee at 12:06 a.m.
In a convention hall still buzzing from Mr. Clinton's speech well after it ended, delegates said they believed the former president had managed to give the defense of Mr. Obama they had been waiting for.
"Some people just have to have it spelled out for them," said Linda Brooks, 64, of Hampton Roads, Va. "He speaks in plain words people can understand."
In the 45-minute speech, Mr. Clinton paid tribute to a spirit of bipartisan political cooperation that he lamented was now missing. He characterized Mr. Obama as a president who wanted to bring that spirit back, noting that the president appointed Republican cabinet secretaries and former political rivals like Vice President Joseph R. Biden Jr. and Mr. Clinton's wife, Secretary of State Hillary Rodham Clinton. The relationship they built, he said, sent a signal abroad.
"Democracy does not have to be a blood sport," Mr. Clinton said. "It can be an honorable enterprise."
The arrival here by Mr. Clinton had the feel of a valedictory, particularly as Mr. Obama arrived on stage at the end of the speech, while thousands of Democrats here thundered their approval. It was, perhaps, a capstone in the political career of Mr. Clinton, who was delivering his eighth speech to a Democratic National Convention.
Mr. Clinton offered a comprehensive, even exhaustive, assessment of Mr. Obama's first-term priorities, from the auto bailout to the health care law. Brandishing statistics with a familiar vigor, he laid out a case that each of Mr. Obama's initiatives had met the Republican litmus test: leaving Americans better than four years ago.
"Is the president satisfied? Of course not, but are we better off than we were when he took office?" Mr. Clinton said, pausing as the crowd roared in approval. He added, "The answer is yes."
Mr. Clinton used the successful economic record of his presidency to offer an illustration of the magnitude of the problems Mr. Obama inherited when he took office in 2009.
"President Obama started with a much weaker economy than I did," Mr. Clinton said. "No president, not me, not any of my predecessors, could have repaired all of the damage he found in just four years."
Following the speech by Michelle Obama on Tuesday night, the appearance of Mr. Clinton was the highlight of the convention's second night and underscored the tight nature of the presidential race. He was invited by Mr. Obama himself, who asked him earlier this summer to become more involved in his re-election campaign.
It was in many ways a poignant evening, in part because it marked the full reconciliation of the two most popular Democrats of the past 30 years, but also because Mr. Clinton has been increasingly talking about his own mortality.
Mr. Clinton's voice was hoarse, as it has often been through his career, but that seemed to do little though to tamp down his energy, enthusiasm or appeal to the crowd.
Mr. Clinton's presence here inspired gratitude among Mr. Obama's aides and followers, particularly given the close nature of the presidential race, but it also stirred at least a degree of speculation about the future of one of America's most prominent political families. For all of Mr. Clinton's ebullient praise of Mr. Obama, he also was seen by some Democrats as setting the stage for his wife's possible return to politics in 2016, a prospect yearned for by many of Mrs. Clinton's supporters.
He made only a quick reference to his wife, drawing laughter from the crowd as he raised another attribute of Mr. Obama, declaring: "Heck, he even appointed Hillary!"
For Mr. Clinton, the speech dramatized the evolution in his relationship with Mr. Obama, from bitter antagonism to cautious embrace and now a full-throated endorsement. People who know both men do not play down the lingering tension between them, a legacy of the 2008 Democratic primary, when Mr. Obama defeated Mrs. Clinton in a fierce battle that seemed to leave Mr. Clinton more wounded than his wife.
"President Obama beat Hillary Clinton for the nomination," said Rahm Emanuel, the mayor of Chicago, who worked for both men. "President Clinton loves his wife. It took him a little longer to get over it; she got a job."
This time, Mr. Clinton may have had the dual purpose of not only defending his wife's boss, but also enhancing her political prospects, should she decide on another presidential run in 2016. Mrs. Clinton, who plans to step down as secretary of state in January, was in Beijing on Wednesday, negotiating with the Chinese on Syria and the South China Sea.
The speech from Mr. Clinton concluded an evening that began on a discordant note when party leaders, at the behest of Mr. Obama, pushed through a vote to change language in their platform to affirm Jerusalem as the capital of Israel. With the hall noisily divided, it took three tries before the vote was declared passed, leaving some delegates grumbling and analysts saying that the organizers had botched the proceedings.
The Jerusalem reference, which was in the 2008 platform, had been dropped this year, prompting criticism from Republicans and pro-Israel groups. Mr. Obama, bowing to pressure, decided to restore the language, even though official American policy is that the status of Jerusalem should be resolved through negotiations.
The second night of the Democratic convention unfolded in a series of hard-hitting speeches aimed directly at the Republican ticket, with speaker after speaker assailing the records of Mr. Romney and Representative Paul D. Ryan, his running mate.
Elizabeth Warren, the Democratic candidate for Senate in Massachusetts, delivered a forceful critique of Mr. Romney's business background and invoked anti-Wall Street language to make her case on behalf of Mr. Obama, who she said would fight tirelessly for the middle class.
"People feel like the system is rigged against them," she said. "And here's the painful part: They're right. The system is rigged. Look around. Oil companies guzzle down billions in subsidies. Billionaires pay lower tax rates than their secretaries."
Tightening their embrace of social issues, the Democrats also showcased Sandra Fluke, the Georgetown Law School graduate who earlier this year became a symbol of women's reproductive rights in a fight over insurance coverage of contraception.
Her speech, which was delayed so it would be included in the network's prime-time coverage, lit into Mr. Romney and his running mate for their positions against abortion rights — and, in Mr. Romney's case, for staying silent initially after the talk show host Rush Limbaugh called her a "slut."
On the eve of Mr. Obama's acceptance speech, a threat of rain and storms prompted convention organizers to move his speech from an outdoor rally at Bank of America Stadium on Thursday to the significantly smaller Time Warner Cable Arena, where the convention is being held.
It was a disappointment for the Obama campaign, which had been working for months to build a crowd of at least 65,000 supporters for the president's speech.