ISTANBUL 

President Joe Biden’s performance in the first US presidential debate on Thursday night drew sharp criticism from observers and potential voters, while for Democrats, it has raised alarms over whether he should even be on the ballot come November.

US website Politico reported overnight that when Biden was not speaking during the debate, he remained frozen behind his podium, with his mouth open and his eyes wide and unblinking for extended periods.

Biden evidently had a tough time during the debate, often giving answers in a hoarse, quiet voice.

According to CNN, an operative who’s worked on campaigns at all levels for over a decade said: "It’s hard to argue that Biden should be our nominee."

One lawmaker told CNN that it's a "disaster," and said: "Trump is coming off as reasonable even if he’s lying 60 miles per hour. Biden is unintelligible."

Former Biden White House communications director and 2020 deputy campaign manager Kate Bedingfield, also a CNN political commentator, characterized Biden's performance as an "atypically bad."

CNN political analyst Van Jones, a former adviser to then-President Barack Obama, said that in the much-hyped debate, Biden faced a test on regaining the confidence of the US but failed to do so.

“We’re still far from our convention and there is time for this party to figure out a different way forward,” he said, without elaborating what that might mean.

“But that was not what we needed from Joe Biden and it’s personally painful for a lot of people."

"It’s not just panic, it’s the pain of what we saw tonight," he said.

One significant Democratic donor and Biden supporter told Politico that it was time for him to wrap up his campaign.

The donor called Biden’s performance the worst in history, adding that the president was so "bad that no one will pay attention to Trump’s lies," referring to Trump’s largely unchallenged falsehoods in the debate.

"Biden needs to drop out. No question about it," said the donor, according to Politico.

'It made me weep'

Three strategists close to potential Democratic presidential candidates said they were "bombarded" with text messages during the debate, Politico also reported.

According to one adviser, they got requests for an alternate candidate.

Longtime New York Times columnist Thomas Friedman called on Biden to withdraw from the race.

"I watched the Biden-Trump debate alone in a Lisbon hotel room, and it made me weep. I cannot remember a more heartbreaking moment in American presidential campaign politics in my lifetime — precisely because of what it revealed: Joe Biden, a good man and a good president, has no business running for re-election," wrote Friedman.

Nicholas Kristof, a fellow Times columnist, also called for Biden to bow out.

"President Biden is a good man who capped a long career in public service with a successful presidential term. But I hope he reviews his debate performance Thursday evening and withdraws from the race, throwing the choice of a Democratic nominee to the convention in August," he wrote.

After the presidential debate, a CNN flash poll found that 67% of viewers believed Trump emerged the winner versus 33% for Biden.

On the poll, Fox News noted a sizeable shift from CNN's 2020 poll, which indicated that 53% of viewers believed Biden won the final debate against Trump that year.

Biden's debate performance raised questions about whether he could win the election and sparked renewed controversy about his mental, physical condition, and age, which Republicans have long questioned, even while dodging signs of mental deterioration in Trump, who is just three years younger.

He is currently the oldest president at 81 years old and would be 86 at the end of a potential second term.

Biden finished ‘strong’: Kamala Harris

Vice President Kamala Harris admitted that Biden had a "slow start" in his debate against former president Donald Trump on Thursday night but argued that he finished “strong.”

"And what became very clear through the course of the night is that Joe Biden is fighting on behalf of the American people – on substance, on policy, on performance,” Harris told CNN.

In a break from previous years, the debate took place prior to the formal nomination of both Biden and Trump at their respective party conventions.

The Democratic National Convention will be held on Aug. 19 in Chicago.

Democrats started to speculate about potential replacements, with one telling CNN, “If I was Gavin (Newsom, California governor) or Gretchen (Whitmer, Michigan governor), I’d be making calls tonight,” one said.

But Newsom, 56, rejected calls for Biden to be removed from the Democratic ticket.

"I will never turn my back on President Biden. Never turn my back on President Biden, I don’t know a Democrat in my party that would do so," he said.