But Mr. McCarthy, the House Republican leader who could become speaker after 2022, says he needs to work with Donald Trump, who “goes up and down with his anger.’’BAKERSFIELD, Calif. — Kevin McCarthy, the House Republican leader, was in an uncharacteristically dark place.It was after the Capitol siege of Jan. 6, and he was getting pounded from all sides. He was being accused, accurately, of promoting President Donald J. Trump’s stolen-election lies. But Mr. Trump was still enraged at him for not doing more, and his supporters had just ransacked Mr. McCarthy’s office.“This is the first time I think I’ve ever been depressed in this job,” Mr. McCarthy confided to his friend, Representative Patrick T. McHenry, Republican of North Carolina. “Patrick, man, I’m down, I’m just really down.”Mr. McHenry told him to gather himself. “You’re dazed,” Mr. McHenry said, recounting the exchange. “You have to try to think clearly.”As the end of the Trump presidency devolved into turmoil and violence, Mr. McCarthy faced a dilemma, one that has bedeviled his party for nearly five years: Should he cut Mr. Trump loose, as many Republicans were urging. Or should he keep trying to make it work with an ousted president who remains the most popular and motivating force inside the G.O.P.?Mr. McCarthy chose the latter, and not for the first time. His extravagant efforts to ingratiate himself with Mr. Trump have earned him a reputation for being an alpha lap-dog inside Mr. Trump’s kennel of acolytes. Nine days after Mr. Trump departed Washington, there was Mr. McCarthy paying a visit to Mar-a-Lago, the former president’s Florida estate, in an effort to “keep up a dialogue” with the volatile former president.“He goes up and down with his anger,” Mr. McCarthy said of Mr. Trump in a series of interviews during a recent 48-hour swing through Indiana and Iowa, and home to Bakersfield, Calif., which he has represented in Congress since 2007. “He’s mad at everybody one day. He’s mad at me one day.”Now, nearly four months after Jan. 6, Mr. McCarthy continues to defend his support for Mr. Trump’s bogus assertions that the election was stolen from him. Friends say that he knows better and is as exasperated by Mr. Trump’s behavior as other top Republicans, but that he has made the calculation that the former president’s support is essential for his ambitions to become speaker after the 2022 elections, when Republicans have a decent chance to win back the House.Pressed on whether he regretted working to overturn President Biden’s 2020 victory, Mr. McCarthy took the position that he did no such thing.“We voted not to certify two states,” he said, referring to Arizona and Pennsylvania, whose slates of electoral votes Mr. McCarthy and fellow Republicans voted to challenge, despite offering no proof of fraud that would have altered the final tallies. But even if the Republicans’ challenge had been successful in those states, Mr. McCarthy argued, the electoral votes would not have been enough to tip the nationwide vote away from Mr. Biden. “And Joe Biden would still be sitting in the White House right now,” he said.So what exactly was he trying to accomplish with his votes against certification on Jan. 6? “That was the only time that we could raise the issue that there was a question in the activities in those states,” Mr. McCarthy said.On Sunday, Mr. McCarthy was further pressed by the “Fox News Sunday” host Chris Wallace, who asked whether Mr. Trump had sided with the Jan. 6 rioters when the president told Mr. McCarthy in a phone call that day, according to a claim by another Republican House member, that the mob was “more upset by the election” than Mr. McCarthy. Mr. McCarthy had called Mr. Trump to tell him the mob had to stop.Mr. McCarthy sidestepped, saying Mr. Trump told him that he would “put something out to make sure to stop this. And that’s what he did, he put a video out later.”“Quite a lot later,” Mr. Wallace replied. “And it was a pretty weak video.”Mr. McCarthy’s dodge speaks to his role as Mr. Trump’s chief envoy to Republicans in power. At 56, he is perhaps the most consequential member of his party in post-Trump Washington in large part because of his chance of becoming the next speaker of the House. Republicans need to win roughly five more seats to reclaim a majority in 2022, a viable prospect given that congressional districts are set to be redrawn and precedent favors nonpresidential parties in midterm elections. In contrast, Senate Republicans — deadlocked 50 to 50 with Democrats — face a treacherous map, with analysts viewing Senator Mitch McConnell of Kentucky, the minority leader, as less likely to command a majority after 2022.Mr. McCarthy knows the surest way to blow up his speakership plans would be to alienate Mr. Trump, who relishes being both a potential kingmaker to his favored candidates and saboteur of those he is determined to punish.“He could change the whole course of history,” Mr. McCarthy said, referring to the prospect that Mr. Trump could undermine Republican campaigns, or leave the party entirely. “This is the tightest tightrope anyone has to walk.”Mr. McCarthy’s current role has positioned him as perhaps the most consequential Republican in post-Trump Washington.Anna Moneymaker/The New York Times‘Like Your Older Brother’Mr. McCarthy and Mr. Trump share some essential traits. Both men are more transactional than ideological, possess a healthy belief in their own abilities to charm and tend to be hyper-focused on the zero sum of politics (i.e., winning and losing). As the leader of a minority caucus, Mr. McCarthy has been less concerned with passing signature legislation or advancing any transformational policy initiatives.His main preoccupation has been doing what it takes to win a majority and become speaker. He has worked feverishly to that end by recruiting candidates, formulating campaign strategies and raising huge sums ($27.1 million in the first quarter of 2021, spread over four targeted funding entities), much of which he has distributed to his members, earning himself the vital currency of their devotion.“Kevin has unified the Republican conference more than John Boehner or Paul Ryan ever did,” said Representative Jim Banks, Republican of Indiana, referring to Mr. McCarthy’s leadership predecessors. “He’s been to my district four times. My donors know him. They have his cell number. Kevin’s capacity to build and maintain relationships is not normal.”As the leader of a historically fractious caucus, Mr. McCarthy’s most effective unifying tactic has been through common opposition to the “radical socialist agenda” of Democrats, particularly Republicans’ designated time-honored scoundrels like Representative Maxine Waters of California, after she said protesters should “get more confrontational” in the event Derek Chauvin was acquitted in the killing of George Floyd.Mr. McCarthy moved quickly to call a House vote to censure Ms. Waters. The measure promptly failed as Democrats charged hypocrisy over Mr. McCarthy’s unwillingness to condemn worse in his own ranks, among them Representative Matt Gaetz of Florida (possible sex trafficking) and Representative Marjorie Taylor Greene of Georgia (support in 2019 for assassinating Speaker Nancy Pelosi, among other incendiary stances on social media).Friends say Mr. McCarthy has little stomach for playing the heavy. “Look, I work with people I don’t get to hire,” Mr. McCarthy said. He shrugs off the presence of “problematic” members as a phenomenon of both sides. “I’m just a simple person,” Mr. McCarthy likes to say, a standard line in his stump speech. “The Senate is like a country club. The House is like a truck stop.” He prefers eating at a truck stop, he said, “a freewheeling microcosm of society” where he would much rather fit in than try to impose order.“Kevin is a little like your older brother,” Mr. McHenry said. “He doesn’t want to be your parent.”Mr. McCarthy knows the surest way to blow up his plans of becoming speaker would be to alienate Mr. Trump.Jason Andrew for The New York TimesWho’s in Charge?Mr. McCarthy took a seat at a family restaurant in Davenport, Iowa, during a recent visit to highlight a disputed congressional race left over from 2020. Representative Mariannette Miller-Meeks, a Republican, had prevailed by six votes over Rita Hart, a Democrat who was appealing the matter to a House committee. Mr. McCarthy accused Democrats of trying to steal the seat, which invited immediate charges of a yawning double standard given how Mr. McCarthy had supported Mr. Trump’s efforts on a much grander scale.Later that day, Ms. Hart conceded defeat, and the dispute was resolved without riots. “This is a good day,” Mr. McCarthy said. But that morning, Mr. Biden had unveiled his infrastructure bill and had called Mr. McConnell, and not Mr. McCarthy, to brief him ahead of time. Mr. McCarthy volunteered that he had not once spoken to Mr. Biden since Inauguration Day, a slight he maintained did not bother him, although the pique in his voice suggested otherwise.“When he was vice president, we would do stuff together,” Mr. McCarthy said. “He would have me up to eat breakfast at his residence.”Mr. McCarthy flashed a photo of himself from his phone with the vice president at the time, separated by tall glasses of orange juice and plates of freshly cut melon and blueberries. Mr. McCarthy, who likes to attend Hollywood award shows and big-ticket galas, brandished phone photos of himself over two days with other eminences, including Mr. Trump, Pope Francis, Arnold Schwarzenegger and Kobe Bryant. There was also one of himself in high school with majestically feathered hair.But he is also a small-town guy who keeps up with old boyhood pals and still seems enamored of having been popular at Bakersfield High School, where he played tight end on the football team. He travels home often to his district lined with swaying oil jacks, spread across California’s agricultural interior, two hours north and a world removed from Los Angeles, not to mention Washington 2,700 miles away.The son of a firefighter, Mr. McCarthy has a shorthand bio that’s well-worn: He won $5,000 in a lottery, left community college to open a deli, learned firsthand the havoc government intrusion can inflict on business owners, sold the deli, earned a marketing degree and M.B.A. at California State University, Bakersfield, and was elected to the California Legislature in 2002.The waitress came over, and Mr. McCarthy ordered fried chicken and chunky apple sauce.The meal landed while he was on hold waiting to be interviewed by Sean Hannity, giving Mr. McCarthy the chance to methodically rip apart his fried chicken. He separated the batter and meat from the bone with savage gusto, and shoveled as much as possible into his mouth before the interview began. His fingers grew greasy, as did his phone.The gist of the Hannity interview was consistent with one of Mr. McCarthy’s recurring themes of late: Democrats are acting in a heavy-handed manner antithetical to Mr. Biden’s conciliatory impulses. This therefore proved that Mr. Biden was not really in charge of his own government, a familiar Republican trope since the popular-so-far Mr. Biden took over.Republicans need to win roughly five House seats next year to reclaim a majority.Anna Moneymaker for The New York Times‘That’s My Job’Mr. McCarthy became the House Republican leader after his party lost its majority in 2018 and Mr. Ryan retired. Republicans came shockingly close to winning back the majority in 2020, despite predictions they would lose seats in a coronavirus-ravaged economy and with an unpopular president leading the ticket. Instead, the party netted about a dozen seats, leaving it only five short. Mr. McCarthy’s colleagues began referring to him as “speaker in waiting.”After the House chamber was evacuated on Jan. 6, Mr. McCarthy retreated to his Capitol office with a colleague, Representative Bruce Westerman, Republican of Arkansas. When it became evident the rioters were breaking in, Mr. McCarthy’s security detail insisted he leave. But Mr. Westerman was left behind in Mr. McCarthy’s inner work area, he said in a recent interview.For protection, Mr. Westerman said he commandeered a Civil War sword from an office display, barricaded himself in Mr. McCarthy’s private bathroom and waited out the siege while crouched on the toilet.Friends describe the postelection period as traumatic for Mr. McCarthy, who publicly perpetuated the fiction that Mr. Trump had won while privately asking him to stop.“Every day seemed worse than the day before,” said Frank Luntz, a Republican pollster and frequent McCarthy sidekick. “He knew the impossible position he was in.”Still, the turmoil never brought Mr. McCarthy to a breaking point with Mr. Trump. “Look, I didn’t want him to leave the party,” Mr. McCarthy said. “Mitch had stopped talking to him a number of months before. People criticize me for having a relationship with the president. That’s my job.”Whenever the former president’s name came up in these interviews, Mr. McCarthy would lower his voice and speak haltingly, wary of not casting Mr. Trump in a way that might upset him. “Is this story going to be all about Trump?” Mr. McCarthy asked, after back-to-back questions on him. He then paused, seemingly bracing for a ceiling fan to drop on his head.Catie Edmondson More