Michelle Obama has defended her husband's record in office in a deeply personal speech to the Democratic National Convention.
Describing herself as America's "Mom-in-Chief", the First Lady said President Obama had stayed true to his core values during his time in the White House.
She told her audience in Charlotte, North Carolina: "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...
"So when people ask me whether being in the White House has changed my husband, I can honestly say that when it comes to his character, and his convictions, and his heart, Barack Obama is still the same man I fell in love with all those years ago."
The First Lady defended her husband's policies on the economy - the election's key battleground - citing tax cuts for working families and small businesses, along with his support for the motor industry.
And she backed the President's controversial "Obamacare" health reforms, which the Republicans have vowed to repeal if they win back the White House.
She said: "He did it because he believes that here in America, our grandparents should be able to afford their medicine...our kids should be able to see a doctor when they're sick...and no one in this country should ever go broke because of an accident or illness."
The primetime keynote address did not mention Republican Presidential hopeful Mitt Romney, but it highlighted the contrasts between her husband's humble origins and his opponent's privileged background and private equity career.
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She said: "He's the same man who started his career by turning down high paying jobs and instead working in struggling neighbourhoods where a steel plant had shut down, fighting to rebuild those communities and get folks back to work...because for Barack, success isn't about how much money you make, it's about the difference you make in people's lives."
The speech also featured impassioned defences of the President's liberal stance on social issues like abortion and gay marriage, which are likely to play a role in the vote.
She finished her speech with an appeal for Americans to put their trust in her husband for another four years.
She said: "We must once again come together and stand together for the man we can trust to keep moving this great country forward...my husband, our President, President Barack Obama."
President Obama - who watched his wife's speech with his daughters in the White House - is expected to formally accept the Democratic Party nomination in a speech in the 73,000-seater stadium on Thursday.