Bill Clinton has delivered a prime-time defence of Barack Obama, nominating the president for a second term in the White House.
Former US president’s 50-minute speech at the Democratic convention in Charlotte, North Carolina, was strongly critical of Republican economic plans.
Bill Clinton launched a full-throated defence of Barack Obama’s policies, saying his economic policies were working.
Barack Obama will take on Republican Mitt Romney in November’s election.
Bill Clinton’s speech is being seen as the high point of a revitalized relationship between the two presidents and as an attempt to boost Barack Obama’s appeal with white working-class voters.
Polls show these traditional Democratic voters are wary of Barack Obama, but Bill Clinton has a strong record in winning their support.
Bill Clinton told the crowd that they would “decide what kind of country you want to live in”.
“If you want a <<you’re on your own, winner take all society>> you should support the Republican ticket,” he said.
“If you want a country of shared opportunities and shared responsibilities – a <<we’re all in it together>> society – you should vote for Barack Obama and Joe Biden.”
Bill Clinton attacked Republicans for blocking further progress on the economic recovery and getting deep into the detail of policy debates.
“In order to look like an acceptable, moderate alternative to President Obama, they couldn’t say much about the ideas they have offered over the last two years,” he said, referring to the Republican convention in Florida a week ago.
Reminding the crowd that Senate Republican leader Mitch McConnell had revealed that their number one priority was to get Barack Obama out of office, he declared: “We’re going to keep President Obama on the job.”
Bill Clinton argued that Barack Obama’s economic policies on taking office had prevented further collapse and begun the recovery, but said he knew that many Americans were still struggling.
He compared Barack Obama’s experience to his own first term in office, when “our policies were working and the economy was growing but most people didn’t feel it yet”.
“No president – not me or any of my predecessors – could have repaired all the  damage in just four years,” he said.
“But conditions are improving and if you’ll renew the president’s contract you will feel it.”
Bill Clinton criticized Republican vice-presidential candidate Paul Ryan, who he said misrepresented Barack Obama’s Medicare policy at last week’s Republican convention.
He argued that Paul Ryan had made the same amount in cuts as part of his plan for the government-sponsored healthcare plan for the elderly.
“It takes some brass to attack a guy for doing what you did,” said Bill Clinton.
He also countered a Republican ad that Barack Obama had weakened the work requirement for welfare, which Bill Clinton signed into law.
“When some Republican governors asked to try new ways to put people on welfare back to work, the Obama administration said they would only do it if they had a credible plan to increase employment by 20%,” Bill Clinton said, adding that the Republican charge was “just not true”.
After the former president finished a lengthy and partially ad-libbed speech, Barack Obama joined him on stage.
They have previously sparred, most notably during the 2008 primaries when Bill Clinton supported his wife Hillary’s bid for the nomination, and they are known not have a close personal bond.
Earlier, House minority leader Nancy Pelosi was just one of a string of speakers who highlighted social causes including women’s issues, and economic concerns such as the future of the auto industry.
Nancy Pelosi warned that “democracy was on the ballot” in November.
“Republicans support opening the floodgates to special interest money and suppressing the right to vote,” she said.
“It’s just plain wrong.”
Senate candidate Elizabeth Warren railed against inequality, saying Mitt Romney’s policy would amount to “I’ve got mine, the rest of you are on your own”.
And Sandra Fluke, a student branded a “slut” by conservative radio host Rush Limbaugh during a row over contraception, made a prime-time appearance calling for action on women’s issues.
In a procedural surprise as Wednesday’s events got under way, the convention reinstated language from the 2008 platform describing Jerusalem as the capital of Israel.
In confusing scenes a voice vote on the language was called three times. Despite loud boos in the audience, convention chair Antonio Villaraigosa said he had determined that two-thirds of the convention had voted in favor.
Reports emerged shortly afterwards that Barack Obama had personally intervened to change the platform’s language.