Newly elected Speaker of the House Kevin McCarthy holds the gavel after he was elected on the 15th ballot at the U.S. Capitol on Jan. 7. (OLIVIER DOULIERY, TNS/The Minnesota Star Tribune)

Opinion editor's note: Editorials represent the opinions of the Star Tribune Editorial Board, which operates independently from the newsroom.

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After a brutal 15-ballot floor battle that included untold concessions, GOP Rep. Kevin McCarthy realized his life's ambition to become speaker of the U.S. House, but the cost could be far steeper than imagined.

For this is no ordinary political victory. The House Republican Caucus remains deeply divided, and its most extreme members, the so-called Freedom Caucus, have now proven that they can go toe-to-toe with McCarthy and force him to grovel. That could be an ominous harbinger on various issues, but most notably on raising the U.S. debt ceiling.

Raising the debt ceiling is a leftover from last month's lame-duck session. Democrats, then marginally in control of the House and Senate, were confronted with a pile-up of issues and opted to vote on what they could rather than risk everything in a protracted battle over the debt ceiling. At stake were a massive appropriations bill needed to sustain government funding and the Electoral Count Reform Act — a vital safeguard for democracy. To be sure, the result was a Hobbesian choice, since failure to pass the appropriations bill would have resulted in a government shutdown.

Yet the debt ceiling continues to loom as a potential threat to the U.S. and even the world economy. Congressional action is needed to raise the level of debt the U.S. can incur to pay its current obligations. If the ceiling is not increased, temporary measures must be taken to finance the government. According to the Committee for a Responsible Federal Budget, once the government hits the ceiling and runs out of temporary measures, "it is no longer allowed to issue debt and soon after will run out of cash-on-hand." The unthinkable result would be a default on current obligations, including Social Security payments, federal employee salaries and veterans benefits.

Republicans' continued willingness to act as if this were just one more wedge issue, one more political game, is irresponsible. The last most serious threat in this game of chicken came in 2011 when Tea Party Republicans (forerunners of today's Freedom Caucus) threatened to let the U.S. default on debts. A deal finally arrived after weeks of negotiations, with just two days to spare. Nevertheless, the stock market was thrown into turmoil, and the government's credit rating was downgraded for the first time in U.S. history.

Extremists in the Republican caucus have already demonstrated no compunctions about gun-to-the-head negotiations. Rep. Matt Gaetz, R-Fla., at one point boasted that "I ran out of things I could even imagine to ask for" in the McCarthy negotiations. It seems unlikely that they would be moved by a potential default.

To secure his position, McCarthy reportedly made concessions that will limit his office's power and could throw government into prolonged gridlock. Among them: a promise to cap government spending at 2022 levels, place limits on defense spending, institute a three-day waiting period before a bill can get a vote, create a special committee to investigate the Justice Department, and reinstate the rule that allows a single legislator to call for replacing the speaker, which resulted in former GOP Speaker John Boehner resigning rather than face such a fate.

Some of those concessions may prove impossible to fulfill. As powerful as he is, the speaker cannot unilaterally cap government spending or cut defense spending. The House passed its rules package late Monday on a mostly party-line vote. House Majority Whip Tom Emmer, R-Minn., told reporters before the vote that the package was "not controversial" despite some non-Freedom Caucus members expressing serious reservations.

One of those voicing concerns was Rep. Tony Gonzales, R-Texas, who joined Democrats in voting against the measure. He said before the vote that he was concerned about the threat of defense cuts. "This has a proposed billions of dollar cut to defense, which I think is a horrible idea when you have an aggressive Russia and Ukraine, you've got a growing threat of China in the Pacific," Gonzales said during the "Face the Nation" television program.

The question now is how McCarthy will fulfill promises made to the hard-liners in his caucus while also navigating deals with Democratic President Joe Biden and a Democratic-led Senate.

Complicating this triumvirate further is the never-to-be-underestimated Senate Minority Leader Mitch McConnell, who, as extremists were thrashing McCarthy, pointedly stood next to Biden in a ceremony to celebrate a bipartisan success: the $1.6 billion infrastructure bill that would help replace a degraded bridge in McConnell's home state of Kentucky.

Resolution on the debt ceiling — without the crippling cuts to spending that Freedom Caucus members are threatening — should be a top priority for Biden, Senate Majority Leader Chuck Schumer, McConnell and Democratic House Minority Leader Hakeem Jeffries. It'll also be a critical test for McCarthy.