CNA Explains: Could Joe Biden be replaced as a contender in the US election, after his debate performance?

American voters – and people watching around the world – were left unimpressed following the United States’ first presidential debate of 2024.

Both Democratic and Republican candidates were heavily lambasted by the media, with President Joe Biden bearing the brunt of criticism.

What happened?

Biden delivered an alarmingly lacklustre performance, stumbling over words in a hoarse voice and losing his train of thought.

He has acknowledged his poor showing but blame it on exhaustion and jetlag, following two trips abroad earlier in June.

Meanwhile, former president Donald Trump, the presumptive Republican nominee, was slammed for unleashing a barrage of falsehoods.

CNN, which hosted the 90-minute debate, said Trump made more than 30 false claims, including on abortion, aid to Ukraine and the results of the 2020 election.

Who won?

Trump. That’s been the unanimous view of observers, at least.

“The debate was very favourable for Trump. If the election was today, he would win,” said Richard Mullaney, executive director of Jacksonville University’s Public Policy Institute.

The former president emerged stronger from the debate as Biden’s age and health were  – yet again – called into question, with concerns rising over the latter’s ability to lead the world’s biggest economy for the next four years.

Editorials in some key newspapers called for Biden to step aside. A headline in the nation’s most influential broadsheet The New York Times read: “To serve his country, President Biden should leave the race”.

Post-debate opinion polls by US media showed that more respondents now think Biden does not have the cognitive health to serve as president.

New York-based political risk consultancy Eurasia Group put Trump at 70 per cent odds to win the presidency and Biden at a 30 per cent chance of being reelected.

Will Biden exit the race?

On Tuesday, Texas congressman Lloyd Doggett became the first in the party to publicly call for Biden to withdraw.

Biden, 81, has been on a campaign blitz seen as damage control.

"I know I'm not a young man, to state the obvious … but I know how to do this job," the president said to huge cheers at a rally the day after the debate.

He has also vowed to stay in the contest during a call with campaign staff and insisted in meetings with Democratic lawmakers and governors that he is fit for reelection.

Biden's unwillingness to step aside in the face of fierce criticism means he would need to be removed from the Democratic Party ticket.

Names being floated include popular cabinet members and Democratic governors like Gavin Newsom from California, Gretchen Whitmer of Michigan and Josh Shapiro of Pennsylvania. 

However, Vice President Kamala Harris is the top alternative to replace Biden if he decides not to continue his reelection campaign, according to sources that Reuters spoke to. 

She may do better than expected.

The consensus view until recently has been that she is unpopular and would struggle against Trump. However, a Reuters/Ipsos poll on Tuesday showed Harris trailed Trump by one percentage point at 42 per cent to 43 per cent, a difference that was well within the poll's 3.5 percentage point margin of error, and significantly a showing statistically just as strong as Biden's.

However, there is still no obvious candidate who would do better than Biden.

Any alternative would be untested and unproven, at least compared with Biden – the only person to have defeated Trump in an election.

Analysts also pointed out the nominee would be appointed, not elected, which could anger a large portion of the Democratic base and fracture unity.

In any case, Harris, Newsom and other top Democrats, including US Secretary of State Antony Blinken, have publicly backed Biden, even though there remains no consensus within the party about whether he should - or even could - be removed.

“Biden has the clear mandate of a majority of the Democratic Party (and) he's the only actor capable of unifying the various factions in the party,” said Clayton Allen, Eurasia Group’s US director.

“The only way to force him out is if he chooses to drop out. We put a 15 per cent chance on Biden leaving the race.”

And so the prospect of Biden not being a candidate seems unlikely if not remote at this stage.

Can Biden recover?

“It will be very, very difficult,” said Jacksonville University’s Mullaney.

“The good news is – there is a lot of time left for Biden. Although, it’s a steep uphill (climb) for him from here.”

The presidential election is four months away, on Nov 5. 

“At this point, it's still very much anyone's game. There's every opportunity for Biden to do damage control, and every opportunity for the Trump campaign to suffer its own headwinds,” said Allen.

Biden’s camp would likely examine how voters in crucial swing states including Pennsylvania, Wisconsin and Michigan are reacting in the aftermath of the debate, he added.

If there’s a concrete swing to the GOP due to Biden’s performance, it would be a major disincentive for the president to go through with the second debate in September, said Allen.

If that turns out to be the case, then he could stick to rallies instead, he suggested.

For Trump’s camp, the focus would be on sticking to the game plan and repeating a debate performance where he was “controlled, well-spoken and calm” for most of it, he added.