On Wednesday morning, two Republicans who hours earlier had toppled Kevin McCarthy as speaker of the House made a well-worn trek to a 19th-century brick townhouse a few blocks away from the Capitol and entered the cluttered sanctuary of Stephen K. Bannon’s recording studio.

Representatives Matt Gaetz of Florida, the instigator of the rebellion, and Nancy Mace of South Carolina, one of seven other Republican defectors, huddled with Mr. Bannon for a morning meeting ahead of a joint appearance on his “War Room” podcast.

“Tectonic plate shift here in the imperial capital,” Mr. Bannon told his listeners at showtime, while directing them to donate to his guests online. “We must stand in the breach now. We have to lance the boil that is K Street in this nation.”

From this cavelike studio not far from where Congress meets, Mr. Bannon, the former Trump adviser, has been stoking the chaos now gripping the Republican Party, capitalizing on the spectacle to build his own following and using his popular podcast to prop up and egg on the G.O.P. rebels.

Mr. Bannon has spent years promoting the lie that the 2020 presidential election was stolen from former President Donald J. Trump, railing against coronavirus mandates and what he refers to as a “criminal invasion of the southern border.” His obsession of late was toppling Mr. McCarthy and taking out what he describes as “uniparty” Republicans who have become indistinguishable from Democrats.

With Mr. McCarthy’s historic downfall this week, his wing of the party has claimed its most prominent trophy.

Mr. Bannon represents a clear through line from the grievance-driven MAGA base to Congress. And his role in the meltdown that played out this week in the House helps explain why the Republican Party appears to be eating its own. He is a vital part of a feedback loop of red-meat media hits and social media posts, online fund-raising and unfettered preaching to an often angry and fervently right-wing base that rewards disruptions and detests institutions.

In past decades, right-wing rebels on Capitol Hill have encountered trouble getting real traction — shunned by lobbyists and big-money political action committees, excluded from leadership suites in the Capitol and disregarded by Fox News. But with the help of Mr. Bannon, who streams live for four hours every weekday, Mr. Gaetz and others don’t need to rely on any of that.

Mr. Bannon casts the agitators as heroes to his devoted MAGA acolytes, and helps boost their small-dollar fund-raising. He participates in calls with members and donors. He offers strategic advice. He hounds Fox News hosts who he argues don’t give them a fair shake. But mostly, he offers an unfiltered platform where individual rabble-rousers can speak directly to the base, known on “War Room” as “the posse,” creating more incentives for them to wreak havoc on the House floor.

For weeks, Mr. Bannon has been strategizing with Mr. Gaetz on the bid to take down Mr. McCarthy, offering himself up as a sounding board as Mr. Gaetz plotted his moves.

“KABOOM,” Mr. Bannon texted a reporter on Monday night, minutes after Mr. Gaetz filed his long-dangled motion to oust the speaker.

He has also encouraged hard-right lawmakers to use the House floor to yank legislation as far to the right as possible — earning themselves media attention in the process. His advice to them: “Get an amendment. Make it as outrageous as possible. Just be on there — don’t worry if you’re not on Fox — we’ll cut it, we’ll play it.”

On Wednesday, Mr. Bannon introduced his guests on his podcasts as the “architects and heroes of yesterday” and gave them airtime to make a fund-raising pitch.

“I do need help because they’re coming after me,” said Ms. Mace, who represents a politically competitive district. “They’ve threatened to dry up all my money. I’ve had multiple members, previous to the vote last night, threaten to withhold fund-raising if I took this vote. It’s a huge amount of pressure. They call your staff, they scare them.” Twice, Mr. Bannon cued her to spell out her campaign website so that listeners could find it.

His audience is still wary of Ms. Mace, a fiscal conservative who leans toward the center on some social issues and voted to hold Mr. Bannon in criminal contempt for defying a subpoena from the Jan. 6 committee.

But Mr. Bannon sees her as a gift. Her vote to oust Mr. McCarthy allowed him and his cohorts to push back on the notion that it was only an angry group of ultra-MAGA hard-liners who had lost faith in Mr. McCarthy.

“Nancy is not a hard-right intransigent lawmaker,” Mr. Gaetz said on the show. “Nancy is a fiscal hawk.”

Ms. Mace has previously called Mr. Gaetz a “fraud” and accused him of opposing Mr. McCarthy because he wouldn’t defend him against “allegations that he sex-trafficked minors.”

But all of that appeared to be water under the bridge the morning after Mr. McCarthy’s ouster. They were, at least temporarily, allies. On Wednesday, they sat next to each other in Mr. Bannon’s basement, where books about China, Trump and sensible weight loss programs live in messy piles on any flat surface that avails itself. Notes from Mr. Trump written in his trademark Sharpie (“Steve! Your show is sooooo great — Proud of you! Donald”) sit stacked with other miscellany.

The group was still digesting the historic events of the previous day, while figuring out their next moves. They decided, together, to use Wednesday’s broadcast to look ahead, rather than to “dunk” on the former speaker.

“He was punching down; it was really ugly last night,” said Ms. Mace, whom Mr. McCarthy targeted at his evening news conference, suggesting she was lying when she claimed he had not kept his word.

During commercial breaks, they mulled who might be the next speaker, but there was no clear answer. “I asked Jim Jordan on the floor yesterday, you’re going to be the next speaker?” Ms. Mace said. She turned to Mr. Gaetz with an idea. “Want to go meet with any of them today, together? Like, Scalise or Jordan or anyone?” He was noncommittal.

Mr. Bannon was, too.

“I’m just going to see how it develops,” he said. “Who’s got the stones to take on the apparatus?”

Mr. Gaetz has described himself to people as a “Bannonite tribalist.”

Mr. Bannon, for his part, is in awe of Mr. Gaetz, whom he compares to Daniel Webster. He credits the Florida Republican with recognizing early on last year how helpful a slim G.O.P. majority could be to the hard right.

“He sat right here in July and talked about how we weren’t going to have a 30- or 40-seat majority, but that was actually going to be better,” Mr. Bannon said. “We were going to have leverage. He’s a very special guy.”

Many of the newer rebels in Congress have relied on Mr. Bannon for backing as they look to make their own mark.

Representative Lauren Boebert of Colorado said she was grateful to him for recently offering her a slot on his show to talk about the southern border, rather than to rehash her embarrassing evening at “Beetlejuice.”

“Steve is an actual trusted source, he understands that my one personal night out does not impact the work that I’ve been doing for four years,” she said. “Steve understands the base and what the base wants. I don’t go on there for the donor aspect, but I’m grateful when folks do chip in.”

Mr. Bannon’s name is often greeted with an eye roll, even among Trump loyalists. He’s seen by some as a man who has made the wrong bet on candidates, like the failed Senate candidate in Alabama, Roy Moore, and has an inflated sense of his own influence. He was charged with defrauding donors who were giving money to build a wall along the southern border, before being pardoned by Mr. Trump. He was sentenced to four months in jail for criminal contempt of Congress for defying a subpoena and is free while he appeals the conviction.

But last week, as Mr. Bannon’s cohort debated amendments to the annual military spending bill on the House floor, Mr. Bannon was glued to C-SPAN like a proud stage parent.

“This is red meat,” Mr. Bannon exulted, as Representative Matt Rosendale of Montana defended an amendment that would prohibit mandatory coronavirus vaccines for service members, referring to the vaccine as an “experimental drug.”

Mr. Bannon, an unrepentant agent of chaos, admits he was spoiling for a government shutdown.

“You create a firestorm now that totally changes things,” he said. “People right now think government is a benefit. I’m going to show government spending as cootie-infested.”

Mr. Bannon is also famously temperamental. He has turned on former friends, like Representative Marjorie Taylor Greene of Georgia, for backing Mr. McCarthy during the speaker’s race and on the debt ceiling deal. She has been blacklisted from the show for months.

But after she said she was opposed to any spending bills that included aid to Ukraine, Mr. Bannon said he was warming back up to her. “There’s always a path back,” he said.

On Wednesday morning, Mr. Bannon and his guests tried to temper their glee.

“Do not allow the posse to get punch drunk,” Mr. Gaetz said on the show. There was more work to do.

Mr. Gaetz and Ms. Mace stayed for three segments of the show, until it was time for Mr. Rosendale to pick up the mantle and fire up the base.

“I’ll talk to you later today,” Mr. Bannon said as Mr. Gaetz showed himself out.