WASHINGTON — President Joe Biden is counting on an important political firewall to help him stave off Democratic defections and save his flagging re-election campaign: leaders of the Congressional Black Caucus.

On Monday, after a wave of congressional Democrats called for the president to step aside as the party’s nominee, Congressional Black Caucus Chair Steven Horsford, D-Nev., reaffirmed his support for Biden in the wake of his disastrous debate performance against former President Donald Trump last month. Horsford’s public support is significant given that he is facing a competitive race this fall.

“President Joe Biden is the nominee and has been selected by millions of voters across the country, including voters here in Nevada,” Horsford said in a statement posted on social media, adding that Nevadans “care about a thriving and equitable economy, taking on big corporations to lower costs and protecting the hard fought freedoms, rights and opportunities we’ve earned.”

“They know President Biden and Vice President Harris are fighting for them. Like me, they don’t want to see Donald Trump back in the White House and are ready to work and VOTE to ensure that doesn’t happen,” Horsford continued. “We’re not going back, we’re moving forward.”

The CBC is set to meet with White House aides Monday evening at the Capitol, and Biden is expected to call in, according to four sources familiar with the matter.

Black voters have been key to Biden’s coalition. In the 2020 Democratic primaries, Black voters in South Carolina resuscitated his campaign and put him on the path to the presidency. In addition to choosing the first Black female vice president, he also nominated the first Black woman to be a Supreme Court justice. And now, keeping the support of Black lawmakers may be key to the president’s political future once again.

During a private call between Democratic committee leaders Sunday, four senior Democrats called on Biden to exit the race, and several other ranking members also voiced concerns about his ability to beat Trump in November.

But on that same call, two former chairwomen of the CBC — Reps. Maxine Waters and Barbara Lee, both California Democrats — “forcefully” defended Biden, according to two sources familiar with their comments.

In addition, another CBC member, Rep. Frederica Wilson, D-Fla., who was not on the Sunday call, issued a statement backing Biden and calling out his critics, saying: “Joe Biden and Kamala Harris defeated Donald Trump in 2020 and they are the Democratic ticket that will do so again this year. Any ‘leader’ calling for President Biden to drop out needs to get their priorities straight and stop undermining this incredible actual leader who has delivered real results for our country.”

“What Democrats need to be doing is stop listening to these political pundits and focus on what’s at stake this election: our democracy,” Wilson continued. “End of story. I stand with Joe Biden and Kamala Harris and so should all Americans.”

The CBC is largely behind Biden, the two sources said, although there are “little cracks” within the powerful group — including the fact that not all CBC members have declared their support for Biden publicly.

“Most members in the Congressional Black Caucus are institutionalists,” a senior aide to a CBC member told NBC News.

“It’s hard to imagine many of them going against an incumbent president that has passed many pieces of major legislation to benefit the Black community, and is connected to President Obama.”

“They’ve all doubled down,” said former Rep. Cedric Richmond, D-La., who was a member of the CBC while in Congress and is now a co-chair of the Biden campaign. “Turbulent times don’t bother them. They’ve been through turbulent times, and they know you muscle through it.”

The Biden campaign did not have an immediate comment for this story.

CBC members also have pushed back against criticism of aging politicians and generally been in favor of Democrats’ seniority system, which rewards the longest-serving members with coveted committee gavels. Black lawmakers currently serve as the top Democrat on five House committees.

Black voters were credited with resuscitating Biden’s left-for-dead presidential campaign in 2020, when then-Majority Whip Jim Clyburn, D-S.C., one of the most powerful Black leaders in Washington, endorsed him ahead of the South Carolina primary and rallied the Black community behind him. Biden would go on that year to win the crowded Democratic primary and later oust Trump from the White House.

But Clyburn has not offered full-throated support for Biden in recent days. Following Biden’s stumbles in the June 27 debate, Clyburn said on MSNBC that he would strongly support Harris, a former CBC member, if Biden should step aside. He also appeared on CNN and suggested the party could hold a “mini primary” ahead of the Democratic National Convention in Chicago next month. 

And while House Minority Leader Hakeem Jeffries, D-N.Y., said after the debate that Biden should stay in the race, the highest-ranking Black lawmaker has spent the past week gathering input from party leaders and rank-and-file members ahead of the House’s return to Washington on Monday.

Seeking to shore up support from the Black community and dispel criticism that he’s not up to the job, Biden last week called into two Black radio shows in the swing states of Wisconsin and Pennsylvania. But the president became embroiled in another controversy when the two radio hosts confirmed that Biden campaign aides had provided questions to ask him in advance.

Still, it’s also notable that there are no Black lawmakers among the five House Democrats who have publicly called on Biden to step aside — Reps. Lloyd Doggett of Texas, Raúl Grijalva of Arizona, Seth Moulton of Massachusetts, Mike Quigley of Illinois, and Angie Craig of Minnesota.

Neither are there any Black lawmakers among the four Democratic committee leaders who on the Sunday call urged Biden to leave the race — Reps. Jerry Nadler of New York, Adam Smith of Washington, Mark Takano of California, and Joe Morelle of New York.

“The president has done a great job. I think the only reason why we’re having this conversation is one horrible debate. That’s what he had. He had one horrible debate,” New York Rep. Greg Meeks, the top Democrat on the Foreign Affairs Committee who participated in the Sunday call, said Monday during an appearance on MSNBC.

A CBC member, Meeks said he had not spoken to Biden since the debate but spent time with him last month in Normandy, France, and heard him deliver a “remarkable speech.”

“The president has led, continues to lead, and the leadership that he has provided has brought the world, the democratic world closer together, to make us all safer together than we would be if we were doing this by ourselves,” Meeks continued. “That is what the authoritarians hope — that we would be divided. The leadership of Joe Biden has prevented that from happening.”

One House Democrat and key Biden ally said Monday they believed that Biden can weather the storm — especially with strong CBC backing and support from other influential Democrats like Massachusetts Rep. Richard Neal, the top Democrat on the Ways and Means Committee.

“People are underestimating strong support for the president from senior members in the caucus like Richie Neal and many of the most respected CBC members,” the Biden ally said.