second time, dispensing hard truths on US economic ills and warning that Republican Mitt Romney would endanger America abroad.
Sketching an agenda to create millions of jobs, cut $4 trillion from the deficit and bolster his nation's strength overseas, Obama refused to abandon the hope of 2008, saying: "know this, America: our problems can be solved."
"When you pick up that ballot to vote - you will face the clearest choice of any time in a generation," Obama said, forecasting fateful choices looming on jobs and taxes and war and peace.
"The path we offer may be harder, but it leads to a better place and I'm asking you to choose that future," he said, warning Romney would gut the middle class and return to "blustering and blundering" abroad. Obama accepts nomination for 2nd term as US Prez
"America, I never said this journey would be easy, and I won't promise that now. Yes, our path is harder - but it leads to a better place. Yes our road is longer - but we travel it together. We don't turn back. We leave no one behind."
Obama also blasted Romney and his vice presidential nominee Paul Ryan, as neophytes that would endanger US national security, comparing their thin resume with his own "tested and proven" leadership.
"My opponent and his running mate are new to foreign policy, but from all that we've seen and heard, they want to take us back to an era of blustering and blundering that cost America so dearly."
"After all, you don't call Russia our number one enemy - and not al Qaeda - unless you're still stuck in a Cold War time warp.
"You might not be ready for diplomacy with Beijing if you can't visit the Olympics without insulting our closest ally.
"My opponent said it was 'tragic' to end the war in Iraq, and he won't tell us how he'll end the war in Afghanistan. I have, and I will."
US President Barack Obama speaks on stage as he accepts the nomination for president during the final day of the Democratic National Convention at Time Warner Cable Arena in Charlotte, North Carolina. AFP Photo
Obama cast his speech as a rallying call for Americans to unite to tear open the gridlock that has paralyzed Washington, warning Romney would fire teachers, impoverish students, all to give more tax breaks to millionaires.
"We've been there, we've tried that, and we're not going back. We're moving forward," Obama said, drawing lusty cheers from 15,000 people packed into a sports arena at the Democratic National Convention in North Carolina.
In many ways, Obama's address was an attempt to reconcile the heady promises of hope and change he dispensed four years ago, with the reality of impossible to meet expectations and an economy still staggering from the Great Recession.
"If you turn away now - if you buy into the cynicism that the change we fought for isn't possible -- well, change will not happen.
"If you give up on the idea that your voice can make a difference, then other voices will fill the void: lobbyists and special interests the people with the $10 million checks who are trying to buy this election.
"Washington politicians who want to decide who you can marry, or control health care choices that women should make for themselves."
Obama also posed as a teller of hard truths, arguing that recovery was bound to be hard from the worst recession in decades.
"You didn't elect me to tell you what you wanted to hear. You elected me to tell you the truth," Obama said.
"And the truth is, it will take more than a few years for us to solve challenges that have built up over decades.
"It will require common effort, shared responsibility, and the kind of bold, persistent experimentation that Franklin Roosevelt pursued during the only crisis worse than this one."
Democrat Roosevelt took power in 1933, amid a banking crisis that threatened American capitalism itself, and steered the country to recovery and through the flames of World War II.
Obama took the convention stage knowing that history suggests a sickly economy often dooms an incumbent president seeking re-election.
The Democratic National Convention, which concludes on Friday, nominated US President Barack Obama as the Democratic presidential candidate. AFP Photo
"On every issue, the choice you face won't be just between two candidates or two parties," Obama said.
"It will be a choice between two different paths for America."
The prime-time address came with Obama waging a too-close-to-call race with Romney, who argues that 8.3 percent unemployment and sluggish growth prove the president is out of ideas and should be sent home to Chicago after one term.
Romney, who made his own convention pitch to voters a week ago, earlier called on Obama to issue a report card to Americans on "forgotten promises and forgotten people."
"Over the last four years, the president has said that he was going to create jobs for the American people and that hasn't happened. Romney is Republican hope
"He said he would cut the deficit in half and that hasn't happened. He said that incomes would rise and instead incomes have gone down.
"This is a time not for him not to start restating new promises, but to report on the promises he made. I think he wants a promises reset."
Read the full text of Barack Obama's speech at Democratic National Convention.
Republican presidential candidate, former Massachusetts gov Mitt Romney speaks in Indianapolis. AP Photo
Clinton Obama's most valuable weapon
In a detailed and passionate endorsement of his former rival, Clinton amplified the central argument of Obama's campaign: that voters face a choice between Democratic policies that lead to broad prosperity or Republican policies that benefit the wealthy at the expense of everyone else. But he didn't stop there.
Frequently veering from his prepared remarks, Clinton tackled important topics that have been largely absent from this tightly scripted convention.
He praised Obama's 2009 stimulus, his expansion of college aid, and his efforts to boost renewable energy.
He explained how Obama's healthcare law would benefit ordinary Americans, and warned that Republican healthcare cuts would hurt the poorest and most vulnerable members of society. He argued that Republicans would deepen the country's fiscal woes and prevent more people from voting. Delegates react to Bill Clinton's speech to DNC
He unraveled Republican attacks on Medicare spending and welfare that have been deemed misleading by independent fact-checkers and warned that proposed Republican cuts to healthcare would hurt the poor and disabled, not just the middle class.
And he tackled a question that initially flummoxed Obama aides when Republicans pressed it last weekend: Are Americans better off than they were four years ago?
"The answer is yes," Clinton said. "But too many people are not feeling it yet."
President Barack Obama waves after former president Bill Clinton addressed the Democratic National Convention in Charlotte. AP Photo
'Bill Clinton made 'racist' remarks about Obama in 2008'
Former US president Bill Clinton had taken a racial jibe at Barack Obama in 2008, saying "this guy would have been carrying our bags", a report claimed.
Clinton allegedly made the racially insensitive remark to Senator Ted Kennedy as he tried to convince the liberal to endorse his wife, Hillary, Obama's rival for the Democratic nomination, according to The New Yorker.
Only days before he will nominate President Obama for re-election in the November 6 presidential polls, the report claimed that in 2008, the former president said of him: "A few years ago, this guy would have been carrying our bags."
The reported comment was similar to the one attributed to Clinton in a 2010 book. Bill Clinton comes back for Obama
"A few years ago, this guy would have been getting us coffee," Clinton was quoted as saying in Game Change, by John Heilemann and Mark Halperin.
Clinton's speech to the Democratic National Convention in Charlotte, isn't until Wednesday night, but the former president is getting attention for remarks he has already made, the New York Post reported.
Clinton has, for example, on earlier occasions called Obama "incompetent" and "an amateur" who has no clue about how the world operates, according to an article in Sunday's post by Edward Klein, author of The Amateur: Barack Obama in the White House.
"Obama doesn't know how to be president," Clinton told friends and political advisers in 2011, the article added.
"He doesn't know how the world works," Clinton had said.
Former president Bill Clinton addresses the Democratic National Convention in Charlotte. AP Photo
Obama leads on Twitter
Republican presidential candidate Mitt Romney now has one million followers on micro blogging site Twitter. Romney achieved this milestone three days after he accepted Republican presidential nomination at the Republican National Convention in Tampa Florida.
"1 million active followers – thanks everyone for your support. Help us keep the momentum going," Romney tweeted on September 2.
However, Romney is far behind his challenger incumbent Barack Obama, the US President, who is seeking his re-election in November.
Obama has more than 19 million followers; that makes him the sixth most followed individual on Twitter.
The list is topped by Lady Gaga who has 29 million followers; followed by Justine Bieber (27 million), Kate Perry (25 million) and Britney Spears (nearly 20 million).
Michelle Obama vs Ann Romney
Ann Romney will press husband Mitt's family values and the couple's personal love story Tuesday in a crucial convention speech designed to humanize the Republican presidential nominee.
Ann Romney addresses the second session of the Republican National Convention in Tampa. Reuters Photo
Speaking to Americans "from my heart about our hearts," the would-be first lady will tell a packed convention center in Tampa, Florida that Mitt Romney is "the man America needs," according to speech excerpts released by the campaign.
The wife of the Republican flagbearer was to use the biggest speech of her life, a prime-time address during the Republican National Convention, to invite Americans into her 43-year marriage to see how the man's commitment to family, hard work and good deeds can help lead the country to a better place.
"I want to talk not about what divides us, but what holds us together as an American family... that one great thing that unites us," she said in the excerpts.
"I read somewhere that Mitt and I have a 'storybook marriage.' Well, in the storybooks I read, there were never long, long, rainy winter afternoons in a house with five boys screaming at once," she said, in reference to raising their five rambunctious sons.
"A storybook marriage? No, not at all. What Mitt Romney and I have is a real marriage," she said, adding that "at every turn in his life, this man I met at a high school dance, has helped lift up others."
She said her husband's personal character would translate into a commitment to help all US residents.
Michelle Obama declared life experiences "make you who you are" in a convention pitch Tuesday to US voters that set up stark contrasts between her husband and wealthy rival Mitt Romney.
"Barack knows the American Dream because he's lived it -- and he wants everyone in this country to have that same opportunity, no matter who we are, or where we're from, or what we look like, or who we love," the First Lady said.
US first lady Michelle Obama speaks to supporters of her husband Barack Obama's re-election campaign Florida. Reuters Photo
She did not mention the Romneys by name but detailed the hardships she and President Barack Obama had endured during hard-scrabble lives that made them acutely aware of the problems they were trying to solve for ordinary Americans.
"Barack was raised by a single mother who struggled to pay the bills, and by grandparents who stepped in when she needed help," she said.
"Barack knows what it means when a family struggles. So in the end, for Barack, these issues aren't political -- they're personal. He knows what it means to want something more for your kids and grandkids."
The speech was clearly intended to draw stark contrasts with Obama's rival in November, a multi-millionaire businessman born into privilege as the son of former presidential candidate and American Motors chairman George Romney. Full text of Michelle's DNC speech
Democrats have made hay out of the wealth issue throughout the presidential campaign, attacking Romney for keeping much of his estimated $250 million fortune in offshore havens and asking why he will not release more tax returns.
"Barack and I were both raised by families who didn't have much in the way of money or material possessions but who had given us something far more valuable - their unconditional love, their unflinching sacrifice, and the chance to go places they had never imagined for themselves," Michelle Obama said.
"For Barack, success isn't about how much money you make, it's about the difference you make in people's lives."