NATO summit puts Biden’s fitness under a microscope

A solid performance during the three-day gathering of North Atlantic Treaty Organization leaders could help shore up his candidacy, reminding voters of his support for the 75-year-old military partnership that his predecessor regularly attacked. Another stumble like his debate against Trump last month could only intensify calls for the 81-year-old commander in chief to exit from the presidential race.

“He has absolutely no room for any sort of mistakes, any sort of trip-ups,” said Rachel Rizzo, a senior fellow at the Atlantic Council. “The sort of gaffes that have become pretty common for Biden and just a factor of who he is as a person and as a president are now going to be seen by European leaders as a broader question of suitability.”

Biden will open the summit with remarks Tuesday, followed by a day of meetings and a dinner at the White House for NATO leaders on Wednesday and a press conference with reporters on Thursday. He’ll also hold bilateral meetings with Ukrainian President Volodymyr Zelensky and new British Prime Minister Keir Starmer.

U.S. Ambassador to NATO Julianne Smith said Monday that she was confident of the president’s abilities, having briefed the president three weeks ago about the summit. “He ended up peppering me with loads of questions that were tough to answer,” she said. “I don’t have concerns.”

But the president’s words will be parsed for any slip-ups or mistakes, as will his stamina, after he struggled during the 90-minute debate to deliver coherent answers. A subsequent interview on ABC did little to ease anxieties.

James Townsend, a senior adviser at the Scowcroft Center for Strategy and Security, said of Biden’s debate performance: “There are gonna be a couple of elephants in the room and that is one of them.”

Asked about Biden’s fitness for the job on Friday, a senior administration official touted the president’s record and longstanding trans-Atlantic relationships.

“Foreign leaders have seen Joe Biden up close and personal for the last three years. They know who they are dealing with, and you know, they know how effective he has been,” the senior administration official told reporters during a Friday call, noting that the president has backed NATO and “stood up to [Russian] President [Vladimir] Putin’s unprecedented aggression against Ukraine.”

National Security Council spokesman John Kirby argued that Biden didn’t need to reassure allies following the debate. “We’re not picking up any signs of that from our allies at all,” he said Monday. “Quite the contrary, the conversations that we’re having with them in advance, they are excited about this summit. They are excited about the possibilities.”

Kirby also said that there would be announcements this week on deterrence capabilities as it relates to Ukraine and the entire alliance. He also said there would be announcements on the defense industrial base and on Ukraine’s path to NATO in the future.

Despite a massive damage-control effort by the White House, including the rare TV interview, Biden is facing pressure to end his re-election bid. At least 10 House Democrats have issued public and private calls for the president to drop out, joining a chorus of donors and party officials expressing concerns. Those cries could get louder this week with lawmakers back in Washington for the first time since the debate.

So far, the president has been defiant in the face of criticism, issuing a letter Monday and calling in to MSNBC’s “Morning Joe” to argue that he had the support of voters and that he was committed to staying in the race. A recent Wall Street Journal survey found 80% of voters believe Biden is too old to run for a second term.

Biden cited his foreign policy record as a reason he should remain his party’s nominee.

“I expanded NATO. I solidified it,” Biden said on MSNBC. “I made sure that we’re in a position where we have a coalition of people of nations around the world to deal with China, with Russia. With everything that is going on in the world. We’re making real progress.”

Some NATO leaders aren’t convinced. Polish Foreign Minister Radoslaw Sikorski issued a warning for Biden on the social-media platform X after the debate:

“Marcus Aurelius was a great emperor but he screwed up his succession by passing the baton to his feckless son Commodus (He, from the Gladiator). Whose disastrous rule started Rome’s decline,” Sikorski wrote. “It is important to manage one’s ride into the sunset.”

NATO Secretary-General Jens Stoltenberg dodged repeated questions about Biden’s health and abilities during a July 5 press conference.

“I have had and continue to have a very good working relationship with President Biden, and I welcome his very strong personal commitment to the alliance and the leadership on Ukraine,” Stoltenberg said.

Biden’s debate performance has prompted America’s allies to question whether they now have to prepare for the ever more likely scenario of a second Trump presidency. Europeans are increasingly on edge about what a Trump return means for NATO, given the former president’s frequent criticism of the trans-Atlantic alliance.

At this week’s summit, NATO leaders are likely to reaffirm the long-term goal to bring Ukraine into the alliance. Trump, by contrast, blamed Western promises to bring Ukraine into the alliance for provoking Russia to invade the country in the first place. During his debate with Biden, Trump said that if he were elected in November he would have the war settled before he even took office on Jan. 20. He didn’t provide details.

The contrast between the views of Trump and Biden will be on sharp display.

“Everything the president does right now, every moment is make or break,” said Heather Conley, president of the German Marshall Fund. “For the country and for U.S. national security, the president needs to have a strong performance.”

Dan Michaels contributed to this article.

Write to Catherine Lucey at catherine.lucey@wsj.com