Democrat Hillary Clinton will make her case for the White House tonight, taking the stage at her nominating convention.
In the biggest speech of her more than 25-year career in public service, Mrs Clinton will sound the themes that will propel her campaign against Republican Donald Trump in the election on 8 November.
It will be Mrs Clinton's turn in the spotlight after days of speeches by party heavyweights such as President Barack Obama, Vice President Joe Biden and First Lady Michelle Obama who all praised Mrs Clinton and cautioned that Mr Trump would be dangerous and divisive.
"Tonight in her speech, Hillary is going to stitch together each of these themes and talk about how this election is really a moment of reckoning for the voters," Mrs Clinton's campaign manager Robby Mook told reporters.
"Are we going to succumb to some very powerful forces that are tearing at our social fabric, that are dividing us, economically and socially, or are we going to come together to solve these problems?" he said.
Mrs Clinton is vying to be the first woman elected president in US history.
Endorsing Mrs Clinton last night, Mr Obama gave an optimistic view of America's future in a speech at the Democratic National Convention in Philadelphia.
"There has never been a man or woman, not me, not Bill [Clinton] - nobody more qualified than Hillary Clinton to serve as president of the United States," Mr Obama said to cheers at the event.
"Tonight, I ask you to do for Hillary Clinton what you did for me. I ask you to carry her the same way you carried me."
After Mr Obama's speech, Mrs Clinton joined him on stage where they hugged, held hands and waved to the crowd.
The pair were rivals in the hard-fought campaign for the 2008 Democratic nomination. After winning that election to become America's first black president, he appointed her his secretary of state.
Speaking to delegates, Mr Obama offered an alternative to Mr Trump's vision of the United States as being under siege from illegal immigrants, crime and terrorism and losing its way in the world.
The moment when @HillaryClinton surprised the #DemConvention by joining an emotional @BarackObama on stage. @rtenewshttps://t.co/tj3U9dg4Lh
— Caitriona Perry (@CaitrionaPerry) July 28, 2016
"I am more optimistic about the future of America than ever before," Mr Obama said at the Wells Fargo Center.
Mr Obama took aim at Mr Trump's campaign slogan and promise to "Make America Great Again."
"America is already great. America is already strong. And I promise you, our strength, our greatness, does not depend on Donald Trump," he said.
"Preach!" members of the crowd shouted. "Best president ever," someone screamed.
Mr Obama listed what he described as a series of advances during his two terms in office, such as recovery from economic recession, the Obamacare healthcare reform and the 2011 killing of al-Qaeda leader Osama bin Laden.
Acknowledging voters' concerns, Mr Obama said he understood frustrations "with political gridlock, worry about racial divisions" and the slow pace of economic growth.
"There are pockets of America that never recovered from factory closures, men who took pride in hard work and providing for their families who now feel forgotten," Mr Obama said.
Democrats have surrounded Mrs Clinton with numerous significant party figures at this week's convention.
By contrast, many prominent Republicans were absent from the party convention that nominated Mr Trump for the White House last week.
But he got a boost in opinion polls from his convention. He had a two-point lead over Mrs Clinton in a Reuters/Ipsos opinion poll released on Tuesday, the first time he has been ahead since early May.
At the convention yesterday, US Senator Tim Kaine, Mrs Clinton's running mate, described Mr Trump as "a one-man wrecking crew" who cannot be trusted in the Oval Office.
