President Joe Biden faced criticism for his performance during a critical night marked by several gaffes, including mistakenly referring to Ukrainian President Volodymyr Zelensky as 'President Putin' and calling Vice President Kamala Harris 'Vice President Trump'.
These incidents have sparked a broader discussion about Biden's leadership and his ability to effectively lead the country, with some calling for him to step down from his position.
A poll released on Thursday showed more than half of Democrats say Biden should end his bid for a second term, and two-thirds of Americans believe he should quit the race.
But the former president and the incumbent remain in a dead heat on 46 percent, according to the Washington Post-ABC News-Ipsos survey.
Biden's campaign was however quietly testing the strength of Vice President Kamala Harris in a potential match-up against Trump, The New York Times reported.
Some of the president's longtime aides are meanwhile discussing how to persuade him that he should step aside, the paper also said, citing anonymous sources.
The White House said the report was "unequivocally" false.
The once-talkative Biden has given fewer news conferences than his predecessors, and recent ones have only been with foreign leaders, restricted to two questions each.
Coupled with a lack of interviews, it has led critics to accuse the White House of shielding the effects of age on America's oldest president.
Biden has called his debate meltdown a "bad night," blaming it on a cold and jet lag.
But Clooney tried to torpedo the narrative that it was a one-off, saying it was "devastating" to admit but the signs were also clear at a June 15 fundraiser in Los Angeles he hosted.
Biden has insisted he is committed to running in November, and with the Democratic party primary votes under his belt there is no real way of forcing him out.
His campaign fought back Thursday with a new ad campaign on the last day of the NATO summit portraying Trump as a "lap dog" of Putin.
NATO allies have also been seeking reassurance about Biden's leadership abilities and over their fears that a return of the isolationist, Putin-praising Trump could spell trouble for the alliance.