With the North Atlantic Treaty Organisation (NATO) summit approaching, diplomats and world leaders are voicing concerns about US President Joe Biden’s age and health issues.

To retain the presidency in the upcoming elections on November 5, Biden is required to prove that he’s ready and strong at the summit, which will be held in Washington next week.

According to Politico, allies want Biden to compete for his second-term against Donald Trump, but they are concerned about his ability to defeat the Republican in the forthcoming elections.

Following the 81-year-old’s poor performance in the first presidential debate against the former president, some European officials have voiced doubts about Biden’s stamina and leadership capabilities.

"It doesn’t take a genius to see that the president is old. We’re not sure that, even if he wins, he can survive four years more," one of the officials of the European NATO stated.

Another EU official remarked: "We all want Biden to have a second term to avoid dealing with Trump again, but this isn’t really reassuring."

Moreover, NATO allies are concerned about how long Biden can keep US support for European defence, since Trump is sceptical about extending support for other countries.

"We’re having more conversations about our own defences since it looks like Trump is coming back," an official from one NATO country said after the debate.

Despite all these concerns, many allies prefer Biden over Trump but are uncertain about Biden’s long-term prospects due to his age.

Democrats, with some reportedly considering urging Biden to withdraw from the race. The president, however, has stated publicly that he remains committed to running for re-election.