President Joe Biden, in a letter to congressional Democrats, stood firm against calls for him to drop his candidacy and called for an "end" to the intraparty drama that has torn apart Democrats since his dismal public debate performance.

Biden's efforts to shore up a deeply anxious Democratic Party came Monday as lawmakers are returning to Washington and confronting a choice: decide whether to work to revive his campaign or edge out the party leader, a make-or-break time for his reelection and their own political futures.

Biden wrote in the two-page letter that "the question of how to move forward has been well-aired for over a week now. And it's time for it to end." He stressed that the party has "one job," which is to defeat presumptive Republican presidential nominee Donald Trump in November.

"We have 42 days to the Democratic Convention and 119 days to the general election," Biden said in the letter, distributed by his reelection campaign. "Any weakening of resolve or lack of clarity about the task ahead only helps Trump and hurts us. It's time to come together, move forward as a unified party, and defeat Donald Trump."

Anxiety is running high as top-ranking Democratic lawmakers are joining calls for Biden to step aside despite his defiance. At the same time, some of the president's most staunch supporters are redoubling the fight for Biden's presidency, insisting there's no one better to beat Trump in what many see as among the most important elections of a lifetime.

As lawmakers weigh whether Biden should stay or go, there appear to be no easy answers.

It's a tenuous and highly volatile juncture for the president's party. Democrats who have worked alongside Biden for years — if not decades — and cherished his life's work on policy priorities are now entertaining uncomfortable questions about his political future. And it's unfolding as Biden hosts world leaders for the NATO summit this week in Washington.

Time is not on their side, almost a month from the Democratic National Convention and just a week before Republicans gather in Milwaukee to renominate Trump as their presidential pick. Many Democrats are arguing the attention needs to be focused instead on the former president's felony conviction in the hush money case and pending federal charges in his effort to overturn the 2020 election.

It's what Biden himself might call an inflection point. As he defiantly says he will only step aside if the Lord almighty comes and tells him to, Democrats in the House and Senate are deciding how hard they want to fight the president to change course, or if they want to change course at all.

In an effort to "get on the same page," House Democratic leader Hakeem Jeffries is convening lawmakers for private meetings before he shows his own preference, according to a person familiar with the situation and granted anonymity to discuss it. He plans to gather Democrats on Monday whose bids for reelection are most vulnerable.

But a private call Sunday of some 15 top House committee members exposed the deepening divide as at least four more Democrats — Rep. Jerrold Nadler of New York, Rep. Jim Himes of Connecticut, Rep. Adam Smith of Washington state and Rep. Mark Takano of California — privately said Biden should step aside.

Nadler, as the most senior ranking member on the call, was the first person to speak up and say that Biden should step aside, according to a person familiar with the call who was granted anonymity to discuss it. He did so aware of his seniority and that it would allow others to join him.

Many others on the call raised concerns about Biden's capability and chance of winning reelection, even if they stopped short of saying Biden should step out of the race.

Still other members, including Rep. Maxine Waters of California and Rep. Bobby Scott of Virginia, both leaders in the Congressional Black Caucus, spoke forcefully in support of Biden, as did Rep. Richard Neal of Massachusetts, the top Democrat on the powerful Ways and Means Committee.

And several lawmakers appeared frustrated that leadership was not providing direction or a path forward, according to people familiar with the call. One Democratic lawmaker said regardless of the decision, the situation has to "end now," one of the people said.

Neal said afterward that the bottom line is Biden beat Trump in 2020 and "he'll do it again in November."

The upheaval also is testing a new generation of leaders, headed by Jeffries and Senate Majority Leader Chuck Schumer. Both New Yorkers have refrained from publicly directing lawmakers on a path forward as they balance diverse opinions in their ranks.

Behind the scenes is Speaker Emerita Nancy Pelosi, who continues to field calls from lawmakers seeking advice about the situation, and is widely viewed as the one to watch for any ultimate decision on Biden's future because of her proximity to the president and vote-counting skills in party politics.

Pelosi spoke up last week, saying Biden's debate performance raised "legitimate" questions he needed to answer, but she has remained supportive of the president. And Biden called her last week when he reached out to other party leaders.

When Biden's prime-time ABC interview on Friday appeared to do little to calm worried Democrats, and some said made the situation worse, Pelosi stepped forward to publicly praise Biden on social media as a "great President who continues to deliver for America's kitchen table." She added, "and we're not done yet!"

Schumer has kept a lower profile throughout the ordeal but will convene Democratic senators Tuesday for their weekly lunch when senators are certain to air many views.

One Democrat, Sen. Mark Warner of Virginia, had intended to gather senators Monday to discuss Biden privately, but a person familiar with his thinking said those conversations will take place in Tuesday's regular caucus luncheon with all Democratic senators.

Another Democrat, Sen. Alex Padilla of California, said it was "time to quit the hand-wringing and get back to door knocking."

Padilla spoke with Biden over the weekend, and urged his campaign to "let Joe be Joe."

"Given the debate, I think the campaign has no choice," Padilla said Sunday, explaining that Biden needs to hold town halls and unscripted events to show voters "the Joe Biden I know, and that most people in American have come to grow and love."

While some deep-pocketed donors may be showing discomfort, strategists working on House and Senate races said they posted record fundraising as donors view congressional Democrats as a "firewall" and last line of defense against Trump.

House Democrats have had some of their better fundraising days yet, including a $3 million haul last Friday night after the debate at an event with former President Barack Obama and Jeffries in New York City. That's on top of $1.3 million that rolled into the Democratic Congressional Campaign Committee during the debate and its immediate aftermath.

Senate Democrats are also seeing a "surge" of support, according to a national Democrat with knowledge of Senate races.

As Democratic candidates campaign alongside Biden, the advice has been to focus on building their own brands and amplifying the way the work that's done in Congress affects their local districts.