Former US Vice-President Joe Biden is launching a bid to the White House as a Democrat leader

Former vice president Joe Biden, a moderate who appealed to working-class voters who deserted the Democrats in 2016 as a key part of his political identity, launched a bid for the White House as the instant front-runner of the party on Thursday.

Joe Biden announced on YouTube and other social media the third presidential bid of his career. He is expected to make his first public appearance as a candidate at a Pittsburgh event featuring members of the union, a key constituency, on Monday.

For months, Biden, 76, was wrestling over whether to run. His candidacy will be faced with numerous questions, including whether he is too old and too centrist for a Democratic Party that seeks fresh faces and is increasingly driven by its more liberal vocal wing.

Biden’s candidacy will offer early hints about whether Democrats are more interested in finding a centrist who can win over the white working-class voters who went for Trump in 2016, or someone who can fire up the party’s diverse progressive wing, such as Senators Kamala Harris of California, Bernie Sanders of Vermont or Elizabeth Warren of Massachusetts.

Joe Biden was one of the more aggressive critics of Trump in the party. Last year, Biden said Trump would “beat the hell” if the two were in high school due to how the president spoke about women. That prompted Trump to call him “Crazy Joe Biden,” claiming on Twitter that if they fought, Biden would “go down quickly and hard, crying all the way.”

After a long period of public indecision, Biden decided against a presidential bid in 2016 as he wrestled with doubts as to whether he and his family were prepared for a grueling campaign while mourning his son Beau, who died of brain cancer in May 2015. He had been urged to run by his son.

This time around, Biden faced some of the same family considerations as he is still coping with Beau’s death while his other son, Hunter, went through a divorce in the midst of a reported Beau’s widow relationship.