Mr Biden’s assessment anticipates a clash between the veteran Washington insider and the more liberal and fresh-faced contenders for the party’s 2020 nomination.

Many Democratic voters, and nearly all major Democratic donors, are keenly interested in Mr Biden’s plans because of their consuming focus on finding a candidate who can beat a president they believe represents a threat to American democracy.

Mr Biden would instantly be the early front-runner if he ran. But he would have to bridge divides in a primary that would test whether Democrats are willing to embrace a moderate white man in his 70s if they view him as the best bet to oust Trump.

“He has the best chance of beating Trump, hands down,” said Senator Tom Carper, Mr Biden’s long-time friend and former colleague. “On a scale of 1 to 10, that’s probably about a 12 for us.”

However, Mr Biden’s scepticism about the field could alienate female and minority voters who are excited that several women and African-Americans are expected to run.

Nominating a white man may also rile some Democrats who are already torn about whether a woman could win in 2020 after Hillary Clinton’s loss. 

Some Democrats are sceptical that a relatively moderate candidate like Mr Biden, who has baggage like supporting the 1990s crime bill that is loathed on the left, would prevail in the primary. 

It is expected he would deliver a message of unity and national healing, rather than the fiery and uncompromising brand of populism that Democratic primary voters elevated in the midterm elections.

“In 2020, Biden-style centrism will become a toxic and losing brand of politics in Democratic primaries,” said Waleed Shahid, a left-wing activist.

The 76-year-old former vice president, who leads the field in initial national and Iowa polls, has not yet told his allies that he has decided to run.

But Mr Biden has indicated that he is leaning towards running and will most likely make a decision within the next two weeks, according to Democrats within and beyond his inner circle who have spoken to him recently.

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