WASHINGTON - Former President Bill Clinton gave a forceful defence of President Barack Obama’s handling of the weak US economy on Wednesday night, with a stinging attack on Republican candidate Mitt Romney in a speech that uplifted Democrats at their Convention in Charlotte, Carolina.Clinton, in a rousing address to a television audience of millions, formally nominated Obama as the Democratic candidate in what is expected to be a tight race against Romney, a wealthy businessman. Minutes later, delegates at the Democratic National Convention began the state-by-state roll call vote to make the nomination official. Obama’s acceptance speech Thursday will mark the climax of the national convention, though Democrats have abandoned plans for Obama to deliver the address at a large football stadium, citing weather concerns.Folksy, long on detail and showing he is still a master orator nearly 12 years after he left office, Clinton gave a more cogent defence of Obama’s actions as president than perhaps the current resident of the White House himself.Cheering delegates heard plentiful criticism of Romney as Democrats responded to last week’s Republican convention, which sought to frame the November vote as a referendum on Obama’s presidency amid high unemployment, sluggish economic growth and mounting federal deficits and debt.President Obama, Clinton said, cannot be blamed for the weak economy he inherited in 2009 and has set the foundations for strong economic growth - if voters will give him more time and re-elect him on November 6. “Listen to me now,” he said. “No president - not me, not any of my predecessors - could have fully repaired all the damage that he found in just four years.”Obama finds himself in a vulnerable position with the US jobless rate at 8.3 per cent, and Clinton’s role was to try to make it easier for him. If Americans “renew the president’s contract, you will feel it,” he said. Clinton received roaring applause from thousands of Democratic supporters who jammed the convention hall.“Folks, whether the American people believe what I just said or not may be the whole election. I just want you to know I believe it. With all my heart I believe it,” he said.Obama joined Clinton on stage after the speech for an image of party unity.The Democrats’ most popular elder statesman, Clinton was once an Obama adversary who has since patched up old wounds. He used a stem-winder of a speech that began in TV’s prime time and stretched way beyond it to urge Americans to give Obama four more years.Clinton capped the second night of the convention with a speech that reminded voters of the budget surpluses and job growth he led in the 1990s during his two terms in the White House.Clinton gave point-by-point criticism of Romney, who is running neck and neck with Obama in opinion polls, and congressional Republicans. He accused Romney of wanting to overhaul government entitlement programs Medicare and Medicaid in a way that would reduce benefits for poor children and seniors, he said.“If he’s elected and he does what he promised to do then Medicare will go broke in 2016,” said Clinton.Romney’s criticism of Obama for allowing states to have waivers from work requirements in a welfare law Clinton signed is misplaced, said the former president.His appearance followed a sometimes chaotic day at the convention, where Obama had to personally intervene to force back into the party platform language declaring Jerusalem to be the capital of Israel.Democrats also scrambled to move Obama’s Thursday night speech indoors. He had wanted to accept the Democratic nomination in an open-air stadium jammed with tens of thousands of supporters to portray an image of strength as he faces a tough re-election fight. But the threat of thunderstorms from remnants of Hurricane Isaac forced convention organizers to switch the speech to a much smaller location, the Time Warner Cable Arena.