Bill Clinton has told Americans he believes "with all my heart” that President Barack Obama saved the economy, had left them better off than four years ago and should be re-elected.The two-term Democratic president, who remains highly popular nearly 12 years after leaving office, delivered a comprehensive, unequivocal and glowing endorsement of Obama’s presidency in a prime-time speech in Charlotte, North Carolina, on Wednesday night."No president, no president - not me or any of my predecessors, no one could have fully repaired all the damage he found in just four years,” Clinton said at the Democratic National Convention in the Time Warner Cable Arena."He has laid the foundations for a new modern successful economy of shared prosperity and if you ever need the president’s contract: You will feel it. You will feel it folks."Folks, whether the American people believe what I said or not may be the whole election, I just want you to know that I believe it. With all my heart I believe it.”Al Jazeera’s Patty Culhane, reporting from Charlotte, said Obama came over to Clinton after the speech to "personally thank him, and to show that they are the closest of friends”.Our correspondent also spoke with Linda Moore Forbes, former deputy political director under the Clinton administration, about the length of Obama’s speech, which was supposed to be 28 minutes but lasted almost an hour."Think of his State of the Union addresses, he would make things up, put things in because he’s there to make a compelling argument and to tell the story,” Forbes said."And no one does it better than he does.”Direct rebuttalClinton, president between 1993 and 2001, said Obama had "stopped the slide into depression, ... knowing all the while that no matter how many jobs were created and saved, there were still millions more waiting, trying to feed their children and keep their hopes alive”.He also offered a direct rebuttal to Republican nominee Mitt Romney’s claim that Obama had not left them better off than they were four years ago."Are we where we want to be? No. Is the president satisfied? No. Are we better off than we were when he took office, the answer is Yes,” Clinton said.Obama joined him on stage at the end of the address, in a symbolic uniting of two Democratic eras, signifying a warming of the relationship between two men who once had testy ties.At the start of his speech, Clinton formally nominated Obama as the Democratic Party’s presidential candidate."I want Barack Obama to be the next president of the United States and I proudly nominate him to the standard bearer of the Democratic Party,” he said."I want a man who believes with no doubt that we can build a new American Dream economy."After last night, I want a man who had the good sense to marry Michelle Obama.”The last remark drew cheers and smiles from the First Lady watching from a box the night after her own convention speech.