NATO officials are concerned that US President Joe Biden might lose the upcoming presidential election, according to a report by Politico on Sunday. Sources connected to NATO believe that Donald Trump's return to office could harm the alliance and undermine the war in Ukraine.

Politico spoke with 20 people connected to NATO or the alliance’s upcoming summit over the past month and found that many allies already had quiet reservations about putting their trust in Biden well before the debate. Now, Biden must convince his counterparts that he’s not only up for the fight but also capable of overcoming a political crisis to remain in it.

"We all want Biden to have a second term to avoid dealing with Trump again, but this isn’t reassuring," an official was quoted as saying by Politico.

The officials are also expressing concerns about Biden’s age and health, according to the report. "We’re not sure that, even if he wins, he can survive four more years," an official was quoted as saying by Politico.

Others added, “It was painful to watch, let’s be honest,” an EU official said of the debate. “We all want Biden to have a second term to avoid dealing with Trump again, but this isn’t really reassuring.”

Earlier this week, Biden appeared confused and incoherent during his first debate with Republican frontrunner Trump last Thursday, reinforcing rather than dispelling ongoing concerns about his cognitive abilities at age 81. His poor performance has led some Democratic politicians, donors, and other supporters to call for his removal as the candidate. 

The main contenders expected on the ballot are Biden and Trump, who have both won enough delegates' votes to be their respective Democratic and Republican parties' presumptive nominees. Trump and Biden are set to debate again on September 10.

Would Trump withdraw from NATO?

The NATO alliance's concerns come from Trump's potential plan to withdraw the United States from the alliance. Earlier this year, Trump emphasized his doubts that NATO would come to the United States' rescue were it to come under attack, in further criticism of the alliance that he has always shown disdain for.

Trump is essentially casting doubt on Article 5 of the NATO Charter, which stipulates collective defense in the event of an armed attack on a member state, saying he did not think the alliance would commit and help his country out.

"We're paying for NATO, and we don't get so much out of it. If we ever needed their help, let's say we were attacked, I don't believe they'd be there. I know the people," he said, addressing a large crowd of supporters.