It is a week of reckoning for Joe Biden.

Twelve days after a halting debate performance that may go down as one of the most damaging in modern American history, the president is fighting for his political survival under intense domestic and global scrutiny.

This week’s Nato summit in Washington DC may be his path to at least a temporary reprieve – or this president’s last stand.

In the past few days, Mr Biden has railed against his critics, claimed the mandate of Democratic primary voters and challenged opponents to step forward and try to unseat him.

He has promised repeatedly that he is moving ahead with his campaign and that the time for second-guessing and hand-wringing is over. That pressing ahead will start at the Nato summit.

Mr Biden will host alliance leaders for three days of meetings and public events culminating in a solo press conference on Thursday afternoon

It is a stage on which Mr Biden, a man well versed in foreign relations, should be comfortable. But it also raises the already high stakes for his presidency, given that a poor showing will have international as well as domestic ramifications.

A mistake could start a political stampede among Democrats that extinguishes his hopes of even making it to the November general election, let alone winning it.

It could also sharpen concerns from European allies who are concerned about the increasing likelihood of a Donald Trump presidency and the dramatic foreign policy shifts that would come with it.

“Biden is entering this week diminished,” said Kristine Berzina, managing director of the German Marshall Fund Geostrategy North.

“We don’t know how he’s going to exit it.”

Foreign leaders concerned

It is understood that many European leaders are anxious about Trump and his foreign policy strategy. The former president has disparaged multilateral international alliances.

Ms Berzina said that in the past two weeks, however, these leaders have been experiencing something new – Biden anxiety.

After his halting debate performance, she says, American allies have begun doubting whether the president is up to the task.

Heading into the Nato summit, they are hoping to see some evidence that his performance that night was an aberration and not reflective of a new normal.

“It is worrisome to have a close ally, your most meaningful ally, falter,” said Ms Berzina.

“So I think there is tremendous hope that Biden passes the test. But if he isn’t able to deliver, it creates more questions about the US’s reliability.”

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Eyes will be on the US president as he attends summit sessions, hosts foreign leaders at the White House and engages in bilateral meetings with key leaders, including newly elected British Prime Minister Keir Starmer.

Even behind closed doors of the Nato meetings, word of Mr Biden’s performance – good or bad – is sure to leak out.

A Democratic Party panic attack

Mr Biden faces an even taller task this week domestically.

The president has pointed to buttressing and expanding Nato in the face of Russian aggression as one of his key accomplishments.

This is something that differentiates his leadership from Trump’s – as well as any Democrats who could potentially replace him on the ballot – and the summit will be his chance to put that on display for the American public.

“Who’s going to be able to keep Nato together like me?” the president said in his interview with ABC’s George Stephanopoulos on Friday. He added that the Nato summit would be a good way to judge his abilities.

“Come listen,” he said. “See what they say.”

But simply clearing low expectations at the Nato summit and the Thursday press conference may not be enough for many of the politicians, pundits, and party activists who are already calling for him to step aside.

“Just having some good appearances is not going to stop the questions,” said Bill Scher, a liberal pundit and editor of Washington Monthly who recently penned a column calling for Mr Biden to step aside for Vice-President Kamala Harris.

“Time was really of the essence to nip all the speculation in the bud, and they wasted a week. There is no clear path out of this situation.”

Mr Scher – a longtime supporter of Mr Biden – says the president’s attempts to push back now with media interviews, letters, and calls to Democratic politicians come after public sentiment has solidified against him.

And once that sentiment is fully cemented in the polls – which could take several weeks – it will probably be too late to cleanly replace him.

“I understand how difficult it has to be when you’re nearing the end of your life and you’re not performing as well as you used to,” Mr Scher said. “Having to come to terms with that in public has to be excruciating.”

But the data that shows Mr Biden losing support and facing defeat in November is becoming increasingly clear.

Polls indicate nearly three-quarters of Americans – and even a majority of Democrats – think the president should stand down. A half-dozen Democratic members of Congress have called for him to abandon his bid, and many others have offered only equivocal support.

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The president continues to say he will press ahead with his campaign, however, and he has the national convention delegates to ensure that he is the Democratic nominee. The decision lies firmly in his hands, and if he can make it through the week without a major misstep, he may, in fact, survive the immediate storm.

The story of this week, however, has been set. It isn’t one of Nato celebrating its 75th year of existence and focusing on the challenges to come.

Instead, it is a narrative that could decide whether Mr Biden can politically live to fight another day.