The party’s 76-year-old senior statesman, whose announcement was expected to arrive via online video post, would become the most experienced and recognized Democrat in the race, a popular former vice president dominating early polls following months — even years — of campaign planning.
Biden, whose working-class appeal remains intact despite nearly half a century in Washington politics, is seen as a comforting, known quantity for American voters who will be vetting some 20 Democrats now officially in the presidential field.
But recent controversy over his tactile style, particularly with women, could dampen a rollout that he envisioned as the final main entry to the Democratic primary battle.
Biden aides remained tight-lipped this week about the early campaign.
But people familiar with the Democrat’s plans told US media that after launching on Thursday, he will head to Pittsburgh, in the swing state of Pennsylvania that Trump won in 2016, to address a labor union gathering Monday, in his first public appearance after throwing his hat in the ring.
The record number of candidates means Biden faces a field of unprecedented diversity as he makes his third run for president, following two unsuccessful attempts in 1988 and 2008.
After the death of his son Beau from cancer, Biden passed on a presidential campaign in 2016.
As he let the suspense over his political plans drag out for months this year, his broad lead has been whittled, with newer and notably young faces gaining ground including moderate South Bend, Indiana Mayor Pete Buttigieg, who at 37 is less than half Biden’s age.
Complicating matters, the last weeks of waiting have been clouded by revelations from multiple women accusing Biden of touching them inappropriately or making them feel uncomfortable with his affection.
Biden, an old-school politician who acknowledges he is quick to offer hugs and shoulder rubs as he forges connections with voters, has not outright apologized for his behavior, but he pledged earlier this month to be “more mindful” about society’s changing boundaries.
He remains atop most recent polls. With 29.3 percent of the vote, Biden leads leftist Senator Bernie Sanders who is at 23 percent, according to a poll aggregate by website RealClearPolitics.
Senator Kamala Harris is third at 8.3 percent, followed by Buttigieg (7.5 percent), progressive Senator Elizabeth Warren (6.5 percent) and former Texas congressman Beto O’Rourke (6.3 percent).
Biden leads the pack largely on the strength of his lifelong political experience — he was elected to the US Senate at just 29 — and his name recognition.
But in the early stages of what will be a heated primary battle, the status of frontrunner is by no means assured.
“The key question is whether Biden’s current support represents more of a floor for him than a ceiling,” Kyle Kondik of the University of Virginia’s Center for Politics told AFP.
“If it’s a floor, he’s in great shape. If it’s a ceiling, his candidacy could fall apart quickly.”
Biden likes to highlight his modest Pennsylvania origins, which could give him a valuable advantage in Rust Belt states that flipped for Trump in 2016.
“Wall Street bankers and CEOs did not build America,” Biden told strikers last week.
“Ordinary, middle-class people build America. And guys that’s not hyperbole, that’s just a simple fact.”
Biden remains popular for the Democratic base, especially among older, moderate and African-American voters, whose mobilization could play an important role in the race.
Biden gained “some genuine goodwill” with voters over his career, over 36 years as a senator and then eight years as Barack Obama’s deputy, said Kondik.
But his victory in the Democratic primary is no given with a full 10 months before the first nominations votes are cast.
In addition to the unsolicited touching controversy and his famous gaffes, Biden’s long legislative record is facing scrutiny, notably his support for a 1990s anti-crime bill that disproportionately impacted African-Americans.
So is his handling of 1990s hearings featuring Anita Hill, a woman who accused US Supreme Court nominee Clarence Thomas of sexual harassment.