Washington — A slow leak of Democratic lawmakers has begun to call for President Biden to withdraw from the race in the wake of his debate performance last month. Capitol Hill will be the focus of attention this week, as Democratic lawmakers face competing arguments about whether Mr. Biden should be the party's nominee. 

So far, six House Democrats have directly called on the president to exit the race:

• Lloyd Doggett of Texas: He became the first Democratic lawmaker to call on Mr. Biden to drop out, saying on July 2 that he was "hopeful that [Mr. Biden] will make the painful and difficult decision to withdraw." 
• Raul Grijalva of Arizona: He told The New York Times on July 3 that what Mr. Biden "needs to do is shoulder the responsibility for keeping that seat — and part of that responsibility is to get out of this race."
• Seth Moulton of Massachusetts: He told CBS Boston on Sunday that George Washington chose not to run for a third term, and Mr. Biden should follow that cue on another term. "I think that can be President Biden's legacy as well," Moulton said. "He defeated Donald Trump once and then he was willing to hand power over to a new generation of leaders. That's the kind of amazing legacy that a great president like Biden deserves."
• Mike Quigley of Illinois: Quigley said on MSNBC on July 5, "Mr. President, your legacy is set. We owe you the greatest debt of gratitude. The only thing that you can do now to cement that for all time and prevent utter catastrophe is to step down and let someone else do this."
• Angie Craig of Minnesota: Craig, who represents a key swing district, said in a statement on July 6, "This is not a decision I've come to lightly, but there is simply too much at stake to risk a second Donald Trump presidency. That's why I respectfully call on President Biden to step aside as the Democratic nominee for a second term as President and allow for a new generation of leaders to step forward."
• Adam Smith of Washington: Smith on Monday called on Mr. Biden to end his candidacy "as soon as possible." He said in a statement that presidential candidates "must be able to clearly, articulately, and strongly make his or her case to the American people. It is clear that President Biden is no longer able to meet this burden." Smith told CBS News that if Biden announced he was ending his bid, "there would be a huge sigh of relief amongst just about every Democrat in the House." 

Still, more congressional Democrats have publicly expressed support for Mr. Biden since the debate. And in recent days, some lawmakers have called for the party to unequivocally back the president, including prominent members of the powerful Congressional Black Caucus. 

Meanwhile, as lawmakers prepared to return to Washington after last week's recess, a group of senior House Democrats met with House Minority Leader Hakeem Jeffries over Zoom Sunday night, where a person on the call and three people familiar with the meeting told CBS News that three more lawmakers said Mr. Biden should leave the race: 

• Jerry Nadler of New York
• Mark Takano of California 
• Joe Morelle of New York

Mr. Biden has been working to address concerns about his ability to serve another term with a number of appearances in recent days, making clear his intention to stay in the race at every turn — from a highly anticipated interview with ABC News anchor George Stephanopoulos on Friday to rallies in Wisconsin and Pennsylvania over the holiday weekend. 

On Monday, the president sent a letter to Democrats in Congress saying he is "firmly committed" to staying in the race and making clear that "I wouldn't be running again if I did not absolutely believe I was the best person to beat Donald Trump in 2024."

The president aimed to shut down discussions about replacing him, arguing that "the voters of the Democratic Party have voted," and had selected him as their presumptive nominee. In March, he surpassed the number of delegates needed to clinch the Democratic Party's nomination, and now has secured 3,896 delegates. There are 1,976 delegates needed to secure the Democratic nomination at the convention in August. Mr. Biden warned that forcing him off the ticket would subvert the will of the voters: "How can we stand for democracy in our nation if we ignore it in our own party?"

Mr. Biden also called into "Morning Joe" on Monday, saying "I'm more than presumptive, I'm gonna be the Democratic nominee." He expressed frustration with "the elites" doubting his fitness for another term, saying "any of these guys that don't think I should run — run against me. Go ahead, announce for President. Challenge me at the convention."

The president has also made outreach efforts in recent days, with a campaign official saying he personally made 20 calls to congressional members since the debate. 

Mr. Biden, who represented Delaware in the Senate for over 30 years, will certainly be watching for signs of wavering support in the upper chamber. No Senate Democrats have publicly called for the president to step aside. And Virginia Sen. Mark Warner scrapped a Monday meeting with a group of Senate Democrats to discuss the president's bid, a source familiar with the senator's thinking confirmed to CBS News. 

Ed O'Keefe, Nikole Killion, Scott MacFarlane and Fin Gómez contributed reporting.

Kaia Hubbard

Kaia Hubbard is a politics reporter for CBS News Digital, based in Washington, D.C.

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