Joe Biden is braced for an onslaught of attacks from the left as Democratic presidential contenders attempt to pin back the front-runner in the first debates of the race, which begin today.
Pollsters and party insiders have predicted the former vice-president will be targeted by his rivals in an attempt to close the substantial lead he enjoys in the opinion polls.
Mr Biden, who is running on a more centrist ticket than many in the field, has already seen his past stances on abortion, crime, climate change and working with political rivals criticised.
One senior Democrat congressional source told 'The Daily Telegraph' that "ganging up" on Mr Biden was likely, while a leading pollster predicted that other hopefuls would be "shooting" for him.
The first debates in the battle to win the Democratic Party's presidential nomination, and with it the right to take on Donald Trump in the November 2020 election, start today. Twenty candidates have made the cut, based on a combination of donation figures and polling. Ten will appear on stage together tonight and then another 10 tomorrow night.
The debates will take place in Miami, Florida - a crucial swing state in the presidential race which Mr Trump won in 2016. It is a key moment in the long road to the 2020 election, marking the first time that Democrat candidates will face each other after months of individual campaigning.
Mr Biden, who served for eight years as Barack Obama's vice-president, has consistently led in polls of Democratic candidates.
However, in a field with a number of prominent left-wing politicians, most notably Bernie Sanders who defines himself as a democratic socialist, Mr Biden risks being framed as a continuity rather than a change candidate.
Larry Sabato, director of the Centre for Politics at the University of Virginia, said Mr Biden's front-runner status gave an incentive to the other politicians to focus their attacks on him during the debates.
"Essentially he's going to have 19 other candidates shooting at his direction. The real question is whether it is withering fire or just the occasional potshot," he said.
A Democrat congressional source said there would be "ganging up" on Mr Biden, but warned the strategy had risks given how little time each candidate will get to speak. (© The Daily Telegraph, London)