For three days, and amid what’s forecast to be sweltering heat, the embattled octogenarian Joe Biden will pause his conventional electioneering to host a high-stakes NATO summit in Washington, DC.

And he’ll need to avoid serious gaffes during this 72-hour marathon of meetings, speeches and dinners if he holds any hope of reelection.

European leaders from 31 nations are arriving in the American capital to mark the alliance’s 75th anniversary. NATO members have united against Russia’s invasion of Ukraine, even if full membership for Kiev remains elusive. Transatlantic ties are strengthening. Finland and Sweden were inducted into the NATO bloc as strategic and well-armed members to held fend off Putin’s Russia. And the number of member nations spending 2 percent or more of their GDP on defence — a bitter point of contention during Trump’s presidency — has grown under Biden’s administration from nine to 23.

But these factoids won’t save Biden, even if he can remember them.

He now faces an almost insurmountable challenge: allaying major concerns about his political candidacy and cognitive wellness while uniting NATO behind Ukrainie.

Host Biden, who recently self-imposed an early curfew and vowed to work fewer hours, will be expected to work late into the night as he attends a series of official events, including the commemorative ceremony on opening night at the Mellon Auditorium, where the alliance's founding North Atlantic Treaty was signed a few years after World War Two on April 4, 1949.

Biden’s remarks on Tuesday evening will focus on NATO’s increasing importance, but a stumbling speech will do little to project the vibrancy and aura of leadership he so desperately needs.

On Wednesday evening, the president will host a dinner for world leaders at the White House, where he’ll need to shake off concerns that he won’t survive four more years in the Oval Office should he win the presidential election this November.

Thursday will test Biden’s stamina further as he’ll lead and take part in a series of high-level meetings with his European counterparts concerning the war in Ukraine and bolstering NATO’s deterrence capabilities.

With the summit taking place in DC, Biden’s team won’t be able to say that a packed overseas travel schedule left the president exhausted and frail, similar to his recent admission that extensive travel ahead of his debate with Trump made him almost “fall asleep on stage.”

Biden’s biggest test — where he won’t have a teleprompter and scripted remarks to fall back on — will be his solo news conference where he’ll field inevitable questions about his fitness for office, and where he’ll be expected to speak lucidly and nonsense-free, traits that were largely absent onstage with Trump.

Trump is not the only Donald Biden has to worry about, though. In an extraordinary public rebuke, Poland’s centrist prime minister, Donald Tusk, told reporters last week that Democrats “definitely have a problem. The reactions have been unambiguous.”

Throughout the summit, Biden will be under intense scrutiny, with fact-checkers, analysts and journalists lingering onto and dissecting his every word, gesture and move. Forgetting or mis-naming a fellow statesperson at the summit — akin to him recently forgetting the name of the Hamas terror group or announcing at a campaign event that he met former German chancellor Helmut Kohl four years after he died — could have overblown ramifications.

That may not be fair, some may say. But equally unfair is him running in an election where he is rapidly exhibiting cognitive decline and is doomed to fail spectacularly, others would quip back.

However, even if he overcomes all of these hurdles, concerns among Democrats and European leaders will likely still linger, not least because Biden’s electoral nightmare is distracting from attempts by allies to bolster Ukraine’s war machine and, eventually, forge a viable path for NATO membership.

While “Ukraine is still the most important topic” among G7 and European leaders, according to Ian Bremmer, president of geopolitical risk consultancy Eurasia Group, “concerns about Biden and growing panic from Europeans about Trump are increasingly distracting from substantive conversations.”

It’s never a pleasant sight to see a well-respected and admired veteran fade in the public eye. But, at times, the sign of a great leader is also to know when to step back and be remembered for the good times at the apex of one’s career, not the ugly decline.

Jonathan Harounoff is a British journalist and author of the forthcoming book Unveiled: Inside Iran’s #WomenLifeFreedom Revolt