Kevin McCarthy has proven more adept at managing his fragile and restive House majority than might have been expected given that it took him a tortuous 15 rounds of balloting to win the speakership.

Yet the California Republican's turbulent eight months holding the gavel could pale in comparison to the coming stormy fall season from which he is not guaranteed to escape with his job.

The House GOP conference returned to Washington reverberating with demands for the impeachment of President Joe Biden, with a showdown escalating over spending that could split the party and shut down the government.

This looming potential train wreck could play out against a backdrop of emerging political tensions that will define the 2024 election. It will test McCarthy's capacity to balance the demands of far-right members -- some of whom see a government shutdown as a legitimate tactic to try to enforce their will -- and more moderate Republicans whose fate next year will determine whether the GOP keeps the House.

Those tensions include:

— The influence, power and future of ex-President Donald Trump, to whom McCarthy pledged fealty after correctly concluding that his standing in the Republican Party would not be dimmed by his attempt to steal the 2020 election and the day of horror when his supporters ransacked the US Capitol. Trump's supporters in the House are pushing McCarthy to open an impeachment inquiry of Biden. It's part of a wider attempt to weaken the president ahead of a potential rematch against the current Republican front-runner and to distract from Trump's massive legal peril ahead of four criminal trials.

Yet McCarthy is in a difficult spot since he doesn't appear to have the votes to open such a probe -- despite warnings by radical members like Florida Rep. Matt Gaetz that his job is on the line if he doesn't. The speaker is again likely to face a dilemma that caused him to make big concessions to hardliners when he won the job, including measures that make it easier to call for a vote to unseat him. Does he appease those members, led by Trump, to keep his job -- even though doing so might not be in the longer-term interests of his party and even his country?

— McCarthy's capacity to cling to his majority will also depend on his ability to navigate the broad struggle at the center of Republican politics -- between sometimes nihilistic forces epitomized by some members of the conservative House Freedom Caucus and other Republicans who worry that embracing such extremism will destroy the GOP's electability among more moderate general election voters. The speaker surprised many of his critics by threading this needle in a showdown over raising the government's borrowing authority earlier this year that defused a possible economic catastrophe. But a deal on spending he cut with Biden merely postponed his clash with his most hardline members, who are now demanding large reductions to expenditures outlined in the agreement. The confrontation could trigger a government shutdown in the coming months -- a potential political headache for McCarthy heading into an election year.

— The future of America's multi-billion dollar arms and ammunition lifeline for Ukraine has been drawn into the nationalist political stew that shapes Republican politics, with Trump loyalists increasingly adopting his calls for an end to the funding. Tensions over Ukraine aid could be a precursor to a shift in the US position on the war if a Republican wins the White House next year, demonstrating how Ukraine's fate will not simply be written by the heroism of its people resisting President Vladimir Putin's unprovoked invasion or Moscow's military strategy. The question of Ukraine aid is one of the issues, which also includes differences over funding the government, splitting the GOP's narrow House majority and its Senate minority.

Senate Republican leader Mitch McConnell on Monday issued a warning to House Republicans as they traveled back to Washington, saying that "If critics of US support for Ukraine disparage the principle that we should oppose adversaries who invade and destroy Western-aligned neighbors, how credible, how credible is their commitment to defend Taiwan or other allies?" the Kentucky Republican said.

McCarthy's first big problem

McCarthy's first big challenge will be to avoid a government shutdown with federal agencies due to run out of cash at the end of the month. The speaker wants to pass a short-term funding bill to postpone the reckoning until later in the fall. But hardliners warned over the summer that they wouldn't support such a move since they consider 2023 spending levels, which such a move would extend, as "bloated."

McCarthy's slender majority gives these members considerable leverage. He could try to pass an interim spending patch by using Democratic votes, but that could risk a rebellion that could lead to conservative members trying to oust him. One key member of the House Freedom Caucus, Texas Rep. Chip Roy, said that he remained opposed to a short-term spending extension, and shrugged off concerns that a government shutdown could cause a political backlash against Republicans. "The shutdown is not the objective, the objective is to force the administration to the table," Roy told reporters on Monday.

Even if McCarthy does somehow manage to pass a short-term extension to government funding, there's no guarantee that he could enact permanent spending bills in the months before the Christmas holidays. Hardline Republicans want massive cuts that would not even be acceptable to Republicans in the Senate, let alone the Democratic White House. But McCarthy must lead a conference that includes some members who see a shutdown as a means of neutering government itself.

McCarthy is in a box over impeachment

The speaker faces similar political dynamics over the question of whether to open an impeachment inquiry of Biden -- a prospect he has raised. Trump's supporters in the House are demanding action over their claims that the president's family was enriched by foreign business dealings done by his son Hunter when his father was vice president. The Republicans haven't so far produced evidence of wrongdoing by Joe Biden or explained which high crimes or misdemeanors, or instances of treason or bribery -- the constitutional standard for impeachment -- could apply to him.

Gaetz upped the pressure last week, writing on X that he could dip into the "tool kit" he fashioned for House Republicans that makes it easier to oust a sitting speaker. "We've got to seize the initiative. That means forcing votes on impeachment. And if @SpeakerMcCarthy stands in our way, he may not have the job long," he wrote. In response, McCarthy upped the ante -- almost daring the Florida lawmaker, who's a strong supporter of Trump -- to move against him. "He should go ahead and do it," the California Republican said Monday when asked about Gaetz's threat.

One of the ways that McCarthy was able to stabilize a thin power base in his first months of office was to co-opt some of the most anti-establishment members of his conference. Georgia Rep. Marjorie Taylor Greene, another one of Trump's most outspoken supporters, became a surprising pillar of support for McCarthy. But she is now warning that she won't vote to fund the government unless the speaker launches an impeachment investigation. "Put the vote to the floor, even if it fails. I guarantee you, if you put it back, it'll pass because every single Republican that votes no to it will get destroyed by their districts," Greene told CNN.

CNN's Melanie Zanona and Annie Grayer reported Monday that there are as many as 30 Republicans who don't believe that there is sufficient evidence against Biden to move to the historic level of an impeachment inquiry. So even if he wanted to initiate impeachment against Biden to save himself, McCarthy may not have the power to do it.

It's often been impossible to see a clear path ahead in which McCarthy can appease competing political forces with the minuscule majority Republicans secured in last year's midterm elections. So far, he's managed to find one -- even if he merely postponed clashes within his conference and weakened his already compromised hold on power. This is partly because there appears to be no rival ready to take him on or anyone who could do any better in taming the tensions that make his speakership so fragile.

Ahead of an autumn that could turn into a political migraine for McCarthy, he is back in a familiar position.