If Joe Biden wants to end his distinguished career with dignity, he ought to withdraw from the race first thing on Thursday morning.

He won’t, of course. Heavyweight brawlers always think they’ve got one big win left until they’re utterly humiliated in the ring, and we caught a glimpse of the brutal potential endgame this evening.

Biden wasn’t taking on just one strong challenger in the form of Kamala Harris on Wednesday evening - the entire undercard surged through the ropes to take shots.

And while Harris used some clever political alchemy to turn jibes from outsider candidates into jabs against her main rival, many of the zingers from the cheap seats landed like body blows on the former vice president.

His performance was not disastrous. There are no clips of him floundering that are bad enough to go viral. But the frontrunner should not look this uncomfortable at this early stage.

Joe Biden and Barack Obama through the years Show all 15 1 /15 Joe Biden and Barack Obama through the years Joe Biden and Barack Obama through the years Joe Biden and Dr Jill Biden watch Barack Obama's farewell speech on 11 January. Obama called Biden his 'brother' Joe Biden and Barack Obama through the years US President Barack Obama speaks alongside US Vice President Joe Biden about the Affordable Care Act AFP/Getty Images Joe Biden and Barack Obama through the years Vice President Joe Biden and President Barack Obama Getty Joe Biden and Barack Obama through the years President Obama listens to Joe Biden speak of his work on defeating cancer on 18 October in the White House Reuters Joe Biden and Barack Obama through the years U.S. President Barack Obama is applauded by House Speaker Paul Ryan and Vice President Joe Biden while delivering his final State of the Union address to a joint session of Congress in Washington Reuters Joe Biden and Barack Obama through the years U.S. Vice President Joe Biden interjects as President Barack Obama delivers remarks at a reception for the 25th anniversary of the White House Initiative on Educational Excellence for Hispanics at the White House in Washington REUTERS Joe Biden and Barack Obama through the years Obama and Vice President Joe Biden react after a heckler was removed for their extended interruption (Reuters) Joe Biden and Barack Obama through the years U.S. President Barack Obama shakes hands with Speaker of the House John Boehner (R) as Vice President Joe Biden looks on Joe Biden and Barack Obama through the years Barack and Michelle Obama and Vice-President Joe Biden observing a moment of silence outside the White House to mark the 13th anniversary of the 9/11 attacks Getty Images Joe Biden and Barack Obama through the years Barack Obama and Joe Biden putt on the White House putting green Getty Joe Biden and Barack Obama through the years President Barack Obama and Joe Biden in April 2013 AFP/Getty Images Joe Biden and Barack Obama through the years January 1, 2013: U.S. President Barack Obama winks as he arrives with Vice President Joe Biden (L) in the briefing room Reuters Joe Biden and Barack Obama through the years President Barack Obama, Vice President Joe Biden and others receive an update on the mission against Osama bin Laden in the Situation Room of the White House May 1, 2011 in Washington, DC Getty Images Joe Biden and Barack Obama through the years Vice-President Joe Biden, right, confirmed that the US was looking at ways of taking legal action against Julian Assange - back in December 2010 GETTY IMAGES Joe Biden and Barack Obama through the years Joe Biden, left, and retired military officers watch President Barack Obama sign orders to close down the detention centre at Guantanamo Bay, Cuba, in January 2009 GETTY IMAGES

This is only the second debate. He’s up against some people who are so obscure that people Google their names in their droves when they utter a half-decent line. He should be able to phone this stuff in.

Kamala Harris did; when no-hope candidates threw barbs at her, she deftly responded before quickly pivoting to attack Biden.

The former vice president appeared to have no such agility, and became a punchbag for Corey Booker, Bill de Blasio, and at one point Kirsten Gillibrand.

If his performance doesn’t improve, he’ll become America’s punchline.

There are four glaring issues with his debating technique.

He’s clearly made a conscious decision to avoid getting into brawls with his rivals. Presumably his team sees it as statesmanlike, and the route that’ll see him coast to the nomination.

But that’s not how it comes across to viewers at home; when an entire stage of people are pointing out Biden’s faults and none of his rivals are being challenged, he doesn’t look presidential, he looks weak. Barack Obama always had a strikingly presidential quality about him long before he won the Oval Office, but he was not above hitting Hillary Clinton with a low blow during the bitter fight for the nomination.

The second is his willingness to be quiet when told to do so.

He’s a politician. He should have things to say. He should have so much to say that it’s near impossible to shut him up.

People want ideas, plans, next steps. A picture of how America would look with each candidate sat in the Oval Office.

But Biden has this bizarre habit of shutting up the instant a moderator asks him to. He’s the only candidate that consistently does this, and while on the surface it seems minor, it’s so unnatural for a politician that it’s utterly jarring.

The third is that he’s rarely on the front foot.

He made a half-decent attempt at responding to the abundance of criticism against him, but that’s not the role of a leader. He never managed to steer the debate or set the agenda. He should be framing, driving and controlling the debate on his own terms.

In the post-debate scrum, David Axelrod – Obama’s former adviser – said that it was in fact Booker who managed to spin a narrative and a story throughout the night. That’s a man who was barely on the radar going into tonight’s debate.

The final major issue is how he deals with his record. No, not the very chequered part that dates back decades – the eight-year period he spent as Obama’s deputy in the White House.

He repeatedly and blatantly tries to bask in the reflected glory of the popular former president, but when it comes to the negative parts of Obama’s record he’s mute. It’s an issue which was deftly called out by Bill de Blasio and Booker on Wednesday night.

Independent Minds Events: get involved in the news agenda

All of these things are fixable - for some candidates. But Biden is 76 and has his tried-and-tested playbook. He’s not moldable, this is who he is. Was he a charming, dedicated senator with a distinguished record? Yes. Was he the perfect foil to a professorial history-making president? Yes. But he’s failed in his bid to become president twice before because, for this job, he’s simply a weak candidate.

So far he’s only had to deal with one strong candidate in a debate, and still struggled.