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President Joe Biden attends a Medal of Honor Ceremony in the East Room of the White House in Washington, DC, on July 3.
CNN  — 

The NATO summit was long planned to celebrate the alliance’s 75th anniversary, to lock in longterm military support for Ukraine and even to future-proof the West against a possible second term for Donald Trump.

But no one expected the meeting in Washington this week to turn into a public test of 81-year-old President Joe Biden’s health and cognitive capacity with his reelection campaign facing an existential moment after his disastrous debate performance.

Biden’s leadership of NATO and lifeline to Ukraine following Russia’s invasion make him the most significant presidential trustee of the alliance since President George H.W. Bush. But his achievements, including Sweden and Finland’s entry into the group, will be eclipsed at the summit by his battle to save his political future.

Every step Biden takes, every gesture he makes, and every word he utters will be under intense scrutiny, especially in unscripted moments after the image of an aged and at times incoherent commander in chief was burned into the minds of 50 million viewers at the CNN debate in Atlanta late last month.

A president who is older than the alliance itself will be under enormous pressure to show vigor and mental clarity at a solo news conference on Thursday. Any hint of confusion or weakness could spark a fresh round of panic among Democrats and derail Biden’s aggressive effort to quell talk of him abandoning his campaign. The president can expect a volley of questions about his health, his medical records and whether he has been hiding the true details of his condition from journalists infuriated by the White House’s handling of the debate fallout.

The press conference will also be a must-see event for Democrats who are demanding he do far more to prove he is fit to serve a second term that would end when he is 86. Sen. Patty Murray, for instance, warned Monday evening, “We need to see a much more forceful and energetic candidate on the campaign trail in the very near future in order for him to convince voters he is up to the job.” It was a strikingly strong statement by the Washington state Democrat that underscored the vulnerability of Biden’s position. She added: “At this critical time for our country, President Biden must seriously consider the best way to preserve his incredible legacy and secure it for the future.”

Biden will also have an important audience overseas. The effects of the president’s advancing age are not just an issue for his political future; they are now the West’s problem given that he is the last defense against a stunning comeback by Trump, who spent his first term berating NATO allies and cozying up to Russian President Vladimir Putin. Trump has suggested he would let Moscow “do whatever the hell they want” and would not honor NATO’s sacred Article 5 mutual defense principle if he considered that a member state had not met the alliance’s defense spending guidelines.

World leaders will be keen to make their own assessment of Biden

Biden’s debacle created a new complication for US allies already formulating plans for a possibility that many of them dread — a Trump victory in November. The world leaders who will spend hours with Biden this week are therefore certain to make their own assessments of the president and his political hopes.

Kurt Volker, a former US ambassador to NATO, said Biden’s partners will arrive in Washington looking for both political and strategic assurances about Biden and the United States’ future role as the leader of NATO. “Is it going to be President Biden? Is he capable of that? Is he going to run for reelection, is he going to get reelected? If so, what does that look like?” Volker told CNN’s Wolf Blitzer on Monday. Allies are also looking toward an uncertain future, Volker said. “Then they worry – if he doesn’t do that and it’s former president Donald Trump coming back, what does that mean for US support for NATO, US support for Ukraine?”

Foreign diplomats and governments are loath to speak about Biden’s plight on the record out of a desire to avoid being dragged into domestic US politics. But diplomats from Europe, Asia and the Middle East expressed disbelief at his debate showing, CNN reported last week. And looking forward to the summit, one European diplomat said leaders from the continent would stay polite and seek to avoid any accusations of interference or taking sides in US politics. But the person added: “Beneath this cool surface, I believe (the) Biden debate is very crucial. … I don’t believe there are many Europeans who could see how Biden could still be a successful candidate.” Another European diplomat said that “every leader arriving in Washington in the coming days will ask questions about (Biden’s position) and there will be lot of speculation, but the NATO echo chamber doesn’t change the US domestic political calculus in any way.”

The furor over Biden’s age is just the latest shock to rattle the certainty that NATO partners placed in the United States as the alliance’s senior member for more than 60 years – through and after the Cold War until Trump’s arrival in the White House. America’s political paroxysms have left many allies, especially in Europe, considering how to protect themselves in an age when Washington is just as likely to be an agent of volatility as stability. Some question whether the US will be there to defend them anymore. “It’s a reality that we have to be prepared for the unpredictability of the US ally,” a European official said.

US officials reject any suggestion of concern among Biden’s partners about his capacity to lead the alliance, even as multiple polls show most Americans believe he is too old to serve a second term. “Foreign leaders have seen Joe Biden up close and personal for the last three years. They know who they are dealing with and how effective he’s been,” a senior administration official said on condition of anonymity. The administration’s national security spokesman John Kirby on Monday denied that foreign leaders needed to be assured about Biden’s capacities. “We’re not picking up any signs of that from our allies at all. Quite the contrary,” he said.

The critical national security substance of the summit is unlikely to be adversely affected by Biden’s political crisis since diplomats and top military brass have been thrashing out deliverables for months. They’ve focused on institutionalizing aid to Ukraine and on the future relationship between the alliance and the Kyiv government and its desire to eventually join the alliance. After months of diplomatic haggling, a draft text of the final summit communique describes Ukraine as having an “irreversible” path to membership, three sources familiar with the deliberations told CNN.

Biden’s political storm shows no sign of abating

These are surreal days in Washington, with a sitting president waging a battle to remain atop his party’s ticket less than four months from Election Day.

On Monday, the president insisted he wasn’t going anywhere even as worried Democratic lawmakers discussed whether Biden would cost his party the House and the Senate as well as the presidency if he remains their presidential candidate. Rep. Adam Smith, the top Democrat on the House Armed Services Committee, joined lawmakers calling for Biden to fold his reelection bid. “We’ve got a good message. The president has shown he is not capable of delivering that message in an effective way,” the Washington state Democrat told CNN’s Jake Tapper on Monday.

After days of conflicting statements about the president’s medical situation, the White House, meanwhile, insisted that it was “not warranted” for the president to have a new cognitive test and didn’t fully explain why a physician who specializes in Parkinson’s disease had held a meeting with the president’s doctor earlier this year. Biden had earlier called into MSNBC’s “Morning Joe” to underscore his refusal to cede his campaign in a manner that indicated that any subsequent request from Democratic leaders for him to leave the ticket would cause an ugly political spectacle.

Biden also seized on the upcoming summit as proof of his leadership skills and success as president, while his campaign sought to use his turn on the global stage on US soil to reset the comparison between him and Trump — the core theme of his campaign, which has been obliterated by his dismal night at the debate.

“The rest of the world is looking — our allies are looking for US leadership. Who else — who else do you think could step in here and do this?” Biden said on MSNBC. In an interview with ABC News on Friday, the president also billed himself as essential to global security. “I’m the guy that put NATO together, the future. No one thought I could expand it. I’m the guy that shut Putin down. No one thought could happen,” Biden said.

The president has not shut Putin down — the brutal Russian daylight air attack on Kyiv that hit a children’s hospital on Monday is proof of that. But he has mustered the most effective arming of a Russian adversary since the US backed the Afghan mujahideen fighting the Soviet Union in the 1980s and has indeed reinvigorated NATO and presided over the two Nordic nations entering the alliance.

On the eve of the summit, Biden’s campaign distributed a memo lauding his leadership in keeping Kyiv standing more than two years after the Russian invasion. “Donald Trump is a threat to NATO, a gift to Putin and a wrecking ball to global peace, democracy and human rights,” the memo read. The campaign also pointed out the presumptive Republican nominee’s frequent genuflecting toward Putin. “The eyes of the world will be on the NATO summit this week, where Joe Biden has strengthened, expanded and led the NATO Alliance against Putin’s violation of Ukraine’s sovereignty and unwarranted aggression.”

It will not be much comfort to Biden, but he is not the only NATO leader who is politically weakened. French President Emmanuel Macron will arrive in Washington after triggering a new era of political instability. His ordering of snap legislative elections to thwart the rise of the extreme right party of Marine Le Pen failed to produce a governing majority and empowered the far-left. German Chancellor Olaf Scholz is weakened after his party and coalition took a beating in European Parliament elections. Canadian Prime Minister Justin Trudeau is facing intense speculation about his future ahead of next year’s general election after his Liberal Party lost an election in a Toronto district it had held for decades.

The thorny question of Biden’s age will also be underscored in summit photos since many of the leaders are far younger than a president born during World War II whose foreign policy expertise is honed from a half century of political experience spanning the Cold War and the increasingly restive period ever since. Italian Prime Minister Giorgia Meloni is 47, for example. And Macron is 46. Trudeau has been in power for nearly a decade but is still only 52. The summit will also mark the international debut of new British Prime Minister Keir Starmer, 61, who was elected last Thursday.

Biden has been a steadfast guide for NATO ever since the Russian invasion of Ukraine in February 2022 and has made the survival of global democracy the cornerstone of his presidency. But he has a far more urgent priority at the summit this week – saving himself.

CNN’s Alex Marquardt contributed to this report.