President Joe Biden attends a ceremony at the White House in Washington, DC, on July 3.
CNN  — 

When dozens of world leaders convene in Washington, DC, for the NATO 75th anniversary summit next week, they won’t only be looking to underscore the unity of the alliance — they will also be carefully watching US President Joe Biden after his poor debate performance last week.

Biden’s showing at the CNN presidential debate was met with shock and concern by diplomats around the world. Now, the president will be under immense pressure to perform well at the high-stakes gathering and show that he is still a viable competitor to former President Donald Trump, multiple diplomats told CNN.

The concern is compounded because many believe Trump poses a threat to the future of NATO. He publicly railed against the alliance during his first term in office and did so again recently on the campaign trail, even going as far as suggesting Russia “do whatever the hell they want” to members who don’t meet defense spending targets.

Questions about Biden and his political future inject further uncertainty into a summit where key allies are also dealing with major political changes. The Labour Party took power in the United Kingdom overnight for the first time in more than a decade, putting a new prime minister — Keir Starmer — in place just days before the start of the summit on Tuesday. On Sunday, the second round of French parliamentary elections is taking place, which could potentially lead to a far-right prime minister taking office in a massive defeat to President Emmanuel Macron’s coalition.

Back in the US, the Biden administration and the president himself have acknowledged that the debate was a bad night for Biden. However, they have downplayed its impact on allies.

“What the world knows, the world has experienced over three and a half years — not one night — is exactly the kind of leadership that he’s brought to bear on problems that are common for so many countries, particularly so many of the democracies around the world,” Secretary of State Antony Blinken said at an event at the Brookings Institute on Monday.

However, as one former senior US diplomat said, there will “certainly be a spotlight” on Biden at the NATO summit.

“How does he look? And how does he sound? And how does he move? Does he look fit? And I suppose he and his team (will) be trying to focus on making him look spry and more with it,” said the former diplomat, who is a veteran of several of NATO summits.

Biden will “undoubtedly” be feeling the pressure to perform well, the former diplomat said.

The three-day summit is highly choreographed, and typically little is left to chance. It is preceded by months and months of prep work, discussion and negotiations among the 32 member countries.

During the summit, there will be numerous opportunities for counterparts to interact with Biden — the North Atlantic Council meeting, formal bilateral meetings, a leader’s dinner. The president will be supported and accompanied to key meetings by Blinken, Defense Secretary Lloyd Austin and other key national security officials. Officials such as Blinken and Austin may have one-on-one meetings with their counterparts as well.

‘Crisis mood’

Diplomats say the chances of Biden making a major blunder at the NATO summit are limited, but one European diplomat said, that even if Biden does well, “This will still leave doubt,” given how poorly he performed at the debate.

“If there is another clear failure, this will feed into the ‘crisis mood,’” this diplomat said.

The allies are not expected to raise Biden’s debate performance with him directly, but it is expected that they will discuss the debate and their observations next week among themselves. Another European diplomat said they believe the debate will be used, “even subconsciously, as a benchmark in all kinds of contexts” between now and Election Day.

CNN has reached out to the White House for comment. One US official said they were not aware of concerns that Biden’s debate performance would overshadow the NATO summit, saying that the leaders have spent a good deal of time with the US president, including last month at the G7 summit in Italy.

However, some diplomats were already concerned about Biden’s endurance that summit. Another source told CNN that British officials who spoke with Biden during the G7 in June assessed he was fine and with it when it came to topics discussed during meetings, but that there was a lot of concern after the debate performance that he did not perform like the same person they interacted with in the meetings.

Adding to the pressure is the increased significance of this year’s NATO summit. The alliance will mark its 75th anniversary and seek to shore up consensus on issues such as support to Ukraine, particularly ahead of a potential change in leadership in the United States.

Trump’s stance on the campaign trail that his adherence to the alliance would be conditional has stirred concerns in the international community. Some question whether Trump will seize the opportunity to again denounce NATO next week. The former US diplomat remarked that “it’s hard to imagine him staying out of it.”

One NATO diplomat told CNN that the attention on Biden next week is a double-edged sword — while they appreciate the immense attention on the summit, there is concern that the actual substance will be lost as all eyes are on the US president.

Meanwhile, the Biden administration has sought to focus attention on the content of the summit and away from Biden’s debate performance.

“Next week, in Washington, DC, as you know, the historic summit is to mark the 75th anniversary of NATO’s founding,” White House press secretary Karine Jean-Pierre said Tuesday. “For 75 years, NATO has kept us and the world safer. And under the president’s leadership, this president’s leadership, our Alliance is stronger, it’s larger, it’s more united than ever.”