REHOBOTH BEACH, Del./WASHINGTON — More Democratic lawmakers on Friday publicly called for President Biden to drop out of the 2024 race, including New Mexico Sen. Martin Heinrich, who is running for reelection is what is supposed to be a safe seat for the party.

But Biden is planning to be back on the trail next week, the chair of his campaign said, making the case that party leaders should look at strong grassroots support for his candidacy and resolve their doubts over whether he should stay in the race for a second term.

Biden, who is isolating in his beach house after getting COVID earlier this week, was not expected to do any public events on Friday. Meanwhile, the Democratic National Convention’s rules committee was set to meet about the virtual roll call vote it plans to hold in early August to ensure the party’s candidate is on the ballot by early state deadlines.

Asked about the scores of headlines reporting that Biden is considering whether to leave the race, his campaign chair Jen O’Malley Dillon told MSNBC’s Morning Joe: “You have heard from the president directly time and again. He is in this race to win and he is our nominee and he’s going to be our president for a second term.”

More Democrats ask Biden to step aside

The party has gone through an excruciatingly public deliberation over the past three weeks after Biden froze up during a debate with former President Donald Trump. Top leaders in Congress have failed to publicly deny a steady drip of leaks that they’ve appealed to Biden to step aside for a younger candidate because they think he can’t win the election.

On Friday — the morning after Trump’s acceptance speech at the Republican National Convention — Sen. Martin Heinrich, D-N.M., became the latest senator to ask Biden to step back.

“By passing the torch, he would secure his legacy as one of our nation’s greatest leaders and allow us to unite behind a candidate who can best defeat Donald Trump and safeguard the future of our democracy,” Heinrich said.

A group of four prominent members from the Congressional Black Caucus, Congressional Hispanic Caucus and the progressive caucus called on Biden to step aside. “We must face the reality that widespread public concerns about your age and fitness are jeopardizing what should be a winning campaign,” said Reps. Jared Huffman, D-Calif., Marc Veasey, D-Texas, Chuy Garcia, D-Ill., and Mark Pocan, D-Wis.

Separately, two more Democratic lawmakers, Rep. Jim Costa, D.-Calif., and Rep. Sean Casten, D-Ill., publicly called on Biden to drop out.

Democratic sources told NPR that they expect more lawmakers will go public with concerns about the president’s viability as a candidate, saying the process will take more time to play out as they watch DNC convention rules committee meetings this weekend.

But, the political arm of the Congressional Hispanic Caucus, BOLD PAC, endorsed Biden. “It is clear that Latino voters will decide the margin of victory in competitive races up and down the ballot this cycle, from California and New Mexico to Arizona, Pennsylvania, Nevada, and Nebraska, said Rep. Linda Sánchez, D-Calif., chair of BOLD PAC.

Biden campaign is pointing to support from grassroots Democrats

O’Malley Dillon said it has been a “tough several weeks” for the campaign but said the party needs to unify.

She said Biden has “the greatest respect for the leaders of our party” – referring to reports about the doubts expressed by congressional leaders and former President Barack Obama.

But O’Malley Dillon pointed to a letter now signed by 1,400 Black women leaders from across the country released this week that strongly backed Biden and urged party leaders to “stop the attacks” against him.

“We reject all efforts to disregard this fact or to circumvent the will of millions of voters” who backed Biden in the primaries, the women said in a signed copy of the letter obtained by NPR.

O’Malley Dillon said that the campaign has “seen some slippage in support” since Biden’s disastrous debate, but said party volunteers have found strong interest on the ground in battleground states.

“People are not moving from Joe Biden to Donald Trump. What they’re doing is they’re saying to us, ‘Can he do it?’ And the president is saying, ‘Yes, I can,'” she said.