Democrat Hillary Clinton will make her case for the White House, facing the tough task of equalling show-stopping speeches by President Barack Obama and others who have embraced her bid to become the first woman elected US president.
Known as a more effective politician in small gatherings than as a big-event speaker, the former secretary of state has a hard act to follow after Mr Obama, Michelle Obama, and Vice President Joe Biden electrified this week's Democratic National Convention in Philadelphia.
Mrs Clinton, 68, will lay out her campaign message to Americans later today, as she accepts the nomination to run against Republican Donald Trump.
She needs to make a convincing argument that she can bring about change while representing the legacy of Mr Obama, who is nearing the end of his second four-year term with high approval ratings.
She also needs to make inroads with voters who find her untrustworthy or unlikable.
In his speech, Mr Obama offered an optimistic view of the United States that he contrasted with Trump's vision of a country in crisis.
Mrs Clinton's top advisers told the New York Times she would highlight the moment of reckoning that they said the country faces - the path of division laid out by Republicans or a way forward, "stronger together".
Chelsea Clinton, who spent eight years of her childhood in the White House when Bill Clinton was president, will introduce her mother on Thursday evening.
Mrs Clinton, a US senator from 2001 to 2009, promises to tackle income inequality, rein in Wall Street and tighten gun control if she wins the White House.
Mr Trump, a 70-year-old New York businessman who has never held political office, is running just ahead of Mrs Clinton in a RealClearPolitics average of recent national opinion polls.
They both garner similarly high "unpopularity" ratings.
The Democratic gathering began on a note of discord on Monday, with backers of Bernie Sanders, the US senator from Vermont who lost the nomination to Mrs Clinton, reluctant to get behind her and noisily booing her name.
Mr Sanders has urged his supporters to support her, and a string of party leaders have warmly endorsed Mrs Clinton.
That contrasted with last week's Republican convention in Cleveland, where many party notables showed their concern about Mr Trump's rhetoric and policies by staying away.
Speakers on Wednesday assailed Mr Trump.
Taking aim at Mr Trump's campaign promise to "Make America Great Again," Mr Obama said: "America is already great. America is already strong. And I promise you, our strength, our greatness, does not depend on Donald Trump."
Mr Biden called Mr Trump an opportunist with no clue about how to make America great.
Vice presidential nominee Tim Kaine, a US senator from Virginia, said Mr Trump was a "a one-man wrecking crew" who could not be trusted in the Oval Office.
Former New York Mayor Michael Bloomberg, a Republican-turned-independent media mogul, attacked Trump's history of bankruptcies and lawsuits and called his presidential bid a "con".