WASHINGTON (AP) — President Joe Biden will shift this week from focusing on campaigning for reelection to hosting a NATO summit. But that won’t quiet the increasingly urgent questions about his precarious political situation now threatening to consume his own party.

European leaders gather in Washington starting Tuesday to celebrating the alliance’s 75th anniversary. Biden will attend a series of official events and hold a news conference.

Congress is also heading back into session, meaning there will be face-to-face meetings where Democratic lawmakers can discuss concerns about Biden’s ability to stay in the presidential race for its final four months — not to mention handle another term in the White House.

Already, five Democratic lawmakers have said the 81-year-old president should step aside. And several Democratic committee leaders privately say that Biden should bow out of the race. They could add to the public clamor in coming days — even as the Biden campaign, and the president himself, make calls to try to curb further defections.

Vice President Kamala Harris is most frequently mentioned as a possible replacement at the top of the Democratic presidential ticket. But Biden has said repeatedly that he’s staying put, and he plans to campaign on Friday in the battleground state of Michigan — which may make internal Democratic Party divisions all the more bitter.

Here’s a look at what’s ahead for Biden:

NATO summit

Biden will have a chance to look presidential, but it comes with another key test.

The summit will focus on Russia’s war with Ukraine, but likely overshadowing all of Biden’s other duties during it is a news conference set for Thursday. His performance there will be as closely scrutinized as his ABC interview last week for further signs of frailty or mental struggles after his disastrous debate against Donald Trump late last month.

Also, those gathering for the summit have discussed “ Trump-proofing,” or safeguarding, NATO against a possible return of Trump to the White House — and those discussions could heat up because of the concerns about Biden’s political future.

The gathering unfolds the week before Republicans gather in Milwaukee to formally nominate Trump, who during the debate simply shrugged when Biden asked him if he would “stay in NATO or you’re going to pull out of NATO?”

More Democratic defections?

Will more Democratic lawmakers call for Biden to abandon his reelection bid this week? Will those who have done so privately make their stances public? Each day Congress is in session, the possibility that more lawmakers will turn on the president could grow.

Biden says his party is still unequivocally behind him. But that case will get harder to make if the ranks of those who have lost faith in the president swell. The Democratic National Convention opens in Chicago on Aug. 19, but the party has said it will nominate Biden via virtual roll-call before the in-person gathering begins — meaning Democrats face an increasingly tight window to pick a side.

House Democratic leader Hakeem Jeffries plans on Monday to gather Democrats who are the most vulnerable in seeking reelection. Senate Democrats are planning to talk about Biden’s future during a regular caucus luncheon on Tuesday.

The Republican-controlled House Oversight and Accountability Committee, meanwhile, has announced plans to call on Biden’s White House physician, Dr. Kevin O’Connor, to appear for a transcribed interview “regarding his medical assessments” of the president. Biden has rejected calls to undergo cognitive testing, saying that he is regularly evaluated medically and that the rigors of being president make his mental and physical acuity clear, which has only focused more attention on O’Connor.

Still a long way to go

Even if Biden is able to quell a potential mutiny within his own party, the four months remaining before Election Day means he will likely have to avoid serious mistakes or gaffes for the duration of the race.

Going long stretches without a major misstep is something he’s failed to do over long stretches throughout his political career. But Biden has also built his political persona on resilience.

He won the presidency in 2020 after failed White House bids in 1988 and 2008. Even in 2020, his campaign looked doomed after embarrassing showings in Iowa and New Hampshire. But Biden rebounded with a resounding primary win in South Carolina, and that was enough for most of the Democratic establishment to line up behind him in the days before Super Tuesday and ensure he coasted to the party’s nomination and eventual matchup against then-President Trump.

During the 2022 midterm elections, meanwhile, Democrats did far better than expected, holding the Senate and only narrowly ceding the House majority to the Republicans. Biden says he’s ready to defy the odds again, even as many in his party seems less and less convinced.

“You’ve been wrong about everything so far. You were wrong in 2020. You were wrong in 2022,” a defiant Biden told reporters traveling with him on Friday. “So, look, we’ll see.”