The Congressional Black Caucus is the largest it has ever been, jumping to 57 members this year after a period of steady growth. The 50-year-old group, which includes most Black members of Congress and is entirely Democratic, is also more diverse, reflecting growing pockets of the Black electorate: millennials, progressives, suburban voters, those less tightly moored to the Democratic Party.

But while a thread of social justice connects one generation to the next, the influx of new members from varying backgrounds is testing the group’s long-held traditions in ways that could alter the future of Black political power in Washington.

The newcomers, shaped by the Black Lives Matter movement rather than the civil rights era, urge Democrats to go on the offensive regarding race and policing, pushing an affirmative message about how to overhaul public safety. They seek a bolder strategy on voting rights and greater investment in the recruitment and support of Black candidates.

Perhaps more significant than any ideological or age divide, however, is the caucus’s fault line of political origin stories — between those who made the Democratic establishment work for them and those who had to overcome the establishment to win.

Representative James E. Clyburn of South Carolina, a Democrat and the most powerful Black lawmaker in the House, said in an interview that the group still functioned as a family. But that family has grown to include people like Representative Cori Bush of Missouri, an outspoken progressive who defeated a caucus member in a hotly contested primary last year, and Representative Lauren Underwood of Illinois, whose district is overwhelmingly white.

“There was not a single member of the caucus, when I got there, that could have gotten elected in a congressional district that was only 4 percent African American,” Mr. Clyburn said, referring to Ms. Underwood.

“We didn’t have people in the caucus before who could stand up and say, ‘I know what it’s like to live in an automobile or be homeless,’” he said of Ms. Bush, whose recent dayslong sit-in on the Capitol steps pushed President Biden’s administration to extend an eviction moratorium.

In interviews, more than 20 people close to the C.B.C. — including several members, their senior aides and other Democrats who have worked with the group — described the shifting dynamics of the leading organization of Black power players in Washington.

The caucus is a firm part of the Democratic establishment, close to House leadership and the relationship-driven world of political consulting and campaigns. However, unlike other groups tied to party leaders, the caucus is perhaps the country’s most public coalition of civil rights stalwarts, ostensibly responsible for ensuring that an insider game shaped by whiteness can work for Black people.

Today, the C.B.C. has swelling ranks and a president who has said he owes his election to Black Democrats. There is a strong chance that when Speaker Nancy Pelosi eventually steps down, her successor will be a member of the group. At the same time, the new lawmakers and their supporters are challenging the group with a simple question: Whom should the Congressional Black Caucus be for?

The group’s leadership and political action committee have typically focused on supporting Black incumbents and their congressional allies in re-election efforts. But other members, especially progressive ones, call for a more combative activist streak, like Ms. Bush’s, that challenges the Democratic Party in the name of Black people. Moderate members in swing districts, who reject progressive litmus tests like defunding police departments or supporting a Green New Deal, say the caucus is behind on the nuts and bolts of modern campaigning and remains too pessimistic about Black candidates’ chances in predominantly white districts.

Many new C.B.C. members, even those whose aides discussed their frustration in private, declined to comment on the record for this article. The leadership of the caucus, including the current chair, Representative Joyce Beatty of Ohio, also did not respond to requests for comment.

Miti Sathe, a founder of Square One Politics, a political firm used by Ms. Underwood and other successful Black candidates including Representative Lucy McBath, a Georgia Democrat, said she had often wondered why the caucus was not a greater ally on the campaign trail.

She recounted how Ms. Underwood, a former C.B.C. intern who was the only Black candidate in her race, did not receive the caucus’s initial endorsement.

In Ms. Underwood’s race, “we tried many times to have conversations with them, to get their support and to get their fund-raising lists, and they declined,” Ms. Sathe said.

Representative Ritchie Torres of New York, a 33-year-old freshman member, said the similarities among C.B.C. members still outweighed the differences.

“It seems one-dimensional to characterize it as some generational divide,” he said. “The freshman class — the freshman members of the C.B.C. — are hardly a monolith.”

Political strategy is often the dividing line among members — not policy. The Clyburn-led veterans have hugged close to Ms. Pelosi to rise through the ranks, and believe younger members should follow their example. They have taken a zero-tolerance stance toward primary challengers to Democratic incumbents. They have recently pushed for a pared-down approach to voting rights legislation, attacking proposals for public financing of campaigns and independent redistricting committees, which have support from many Democrats in Congress but could change the makeup of some Black members’ congressional districts.

And when younger members of Congress press Ms. Pelosi to elevate new blood and overlook seniority, this more traditional group points to Representatives Maxine Waters of California and Bennie Thompson of Mississippi — committee chairs who waited years for their gavels. The political arm of the Black caucus reflects that insider approach, sometimes backing white incumbents who are friends with senior caucus leaders instead of viable Black challengers.

Representative Gregory Meeks of New York, the chairman of the caucus’s political action committee, said its goal was simple: to help maintain the Democratic majority so the party’s agenda can be advanced.

“You don’t throw somebody out simply because somebody else is running against them,” he said. “That’s not the way politics works.”

In a special election this month in Ohio to replace former Representative Marcia Fudge, the newly appointed housing secretary and a close ally of Mr. Clyburn’s, the caucus’s political arm took the unusual step of endorsing one Black candidate over another for an open seat. The group backed Shontel Brown — a Democrat who is close to Ms. Fudge — over several Black rivals, including Nina Turner, a former state senator and a prominent leftist ally of Senator Bernie Sanders of Vermont.

Mr. Meeks said the caucus had deferred to its ranking members from Ohio, including Ms. Beatty and Ms. Fudge. Mr. Clyburn also personally backed Ms. Brown. In the interview, he cited a comment from a campaign surrogate for Ms. Turner who called him “incredibly stupid” for endorsing Mr. Biden in the presidential primary race. “There’s nobody in the Congressional Black Caucus who would refer to the highest-ranking African American among them as incredibly stupid,” Mr. Clyburn said.

Ms. Turner, a progressive activist, defended the remark and said the caucus’s endorsement of Ms. Brown “did a disservice to the 11 other Black candidates in that race.” She argued that Washington politics were governed by “a set of rules that leaves so many Black people behind.”

“The reasons they endorsed had nothing to do with the uplift of Black people,” Ms. Turner said, citing her support of policies like reparations for descendants of enslaved people and student debt cancellation. “It had everything to do about preserving a decorum and a consensus type of power model that doesn’t ruffle anybody’s feathers.”

Privately, while some Black members of Congress were sympathetic to Ms. Turner’s criticism, they also regarded the comment about Mr. Clyburn as an unnecessary agitation, according to those familiar with their views.

Last year, several new C.B.C. members across the political spectrum grew frustrated after concluding that Democrats’ messaging on race and policing ignored the findings of a poll commissioned by the caucus and the Democratic Congressional Campaign Committee. The poll, obtained by The New York Times, urged Democrats in swing districts to highlight the policing changes they supported rather than defending the status quo.

But the instruction from leaders of the caucus and the Democratic campaign committee was blunt: Denounce defunding the police and pivot to health care.

“It was baffling that the research was not properly utilized,” said one senior aide to a newer member of the Black caucus, who spoke on the condition of anonymity to voice the frustrations. “It could have helped some House Democrats keep their jobs.”

Mr. Clyburn makes no secret of his disdain for progressive activists who support defunding the police. In the interview, he likened the idea to “Burn, baby, burn,” the slogan associated with the 1965 Watts riots in California.

“‘Burn, baby, burn’ destroyed the movement John Lewis and I helped found back in 1960,” he said. “Now we have defunding the police.”

Mr. Meeks, the political point man for the caucus, said he expected its endorsements to go where they have always gone: to Black incumbents and their allies. Still, he praised Ms. Bush’s recent activism as helping to “put the pressure on to make the change happen,” a sign of how new blood and ideological diversity could increase the caucus’s power.

But Ms. Bush won despite the wishes of the caucus’s political arm. And those who seek a similar path to Congress are likely to face similar resistance.

When asked, Mr. Meeks saw no conflict.

“When you’re on a team,” he said, “you look out for your teammates.”