Speaker Kevin McCarthy is facing an extraordinary referendum on his leadership of the House after a conservative member of his own Republican majority, a longtime critic, moved to launch a vote to oust him from the helm.Late Monday, Rep. Matt Gaetz, R-Fla., rose in the chamber as the House was almost done for the day to file the motion — a resolution that would set a snap vote in coming days that even Gaetz acknowledged may not have enough support to remove the speaker from the job."I have enough Republicans where at this point next week, one of two things will happen: Kevin McCarthy won't be the speaker of the House or he'll be the speaker of the House working at the pleasure of the Democrats," Gaetz told reporters afterward outside the Capitol.McCarthy responded minutes later on social media, "Bring it on."Gaetz soon retorted in a post, "Just did."It's a historic moment: the first time in more than 100 years that a lawmaker has actually used an obscure legislative tool that has been threatened at times against other House speakers, but never fully employed to try to remove them.The bold strike to confront McCarthy carries potentially dire ramifications if enough lawmakers decide to remove his hold on the gavel, but also for Gaetz if it fizzles out. It also puts on stark display the warring factions that have roiled the Republican majority this year in the House and beyond.So far, despite the deep divides over McCarthy's leadership, only a handful of hard-right Republicans have signaled they are willing to vote to remove him. Others who have aligned with Gaetz on spending cuts or other priorities are parting ways with him on this one."It's a really bad idea," said Rep. Thomas Massie, R-Ky., one of the more conservative lawmakers in the House.Gaetz has for months threatened to use the procedural tool — called a motion to vacate — to try to strip McCarthy of his office. Those threats escalated over the weekend after McCarthy relied on Democrats to provide the necessary votes to fund the government.That decision has set McCarthy up for what will likely be the ultimate test of his leadership and may force him to again look across the aisle to Democrats for support. But how the vote will ultimately unfold remains unclear as Democrats weigh whether to help McCarthy, join the effort to oust him or simply withhold their votes or rely on parliamentary maneuvering that could sway the outcome."Do we side with a sociopath or an incompetent?" said Rep. Mark Pocan, D-Wis., a progressive leader. "I don't know?"And allies of McCarthy have said for weeks they were ready for a motion to come.Rep. Michael McCaul, R-Texas, the chairman of the Foreign Affairs Committee, said he has spoken privately to some Democrats who have told him they would vote to help McCarthy remain in office. "I'm sure Mr. Gaetz will have some allies who will go with him. But I don't see enough."The vote ahead could result in humiliation — the first speaker ever ousted from the job through such a motion — or newfound strength as he overcomes yet another obstacle while trying to lead a narrow, unwieldy majority.Conservative critics have been hounding McCarthy from the start, denying him votes and thwarting his plans. But McCarthy has leaned into the fight and suggested it's an opportunity to set aside his critics once and for all.Gaetz acknowledged the effort is likely to fail. He responded to questions about what he hoped to accomplish by saying Americans need to know who's in charge.In a speech on the House floor earlier in the day, Gaetz accused McCarthy of making a deal with the White House during funding negotiations to bring forward legislation to help fund Ukraine in its war against Russia.Brushing off the threat, McCarthy told reporters earlier at the Capitol, "I'm focused on doing the work that has to be done." He added that there was "no side deal" on Ukraine, noting he has not spoken to Biden.A motion to vacate is a rare and strong procedural tool that has only been used twice in the past century against Republican speakers. But in recent years, conservatives have wielded the motion as a weapon against their leaders.In January, McCarthy, hoping to appease some on the hard right like Gaetz as he fought to gain their vote for speaker, agreed to give as few as five Republican members the ability to initiate a vote to remove him. But when that wasn't good enough for his critics, he agreed to reduce that threshold to one — the system that historically has been the norm.The motion Gaetz introduced is a privileged resolution, a designation that gives it priority over other measures. The next step is for House leaders to schedule a vote on the resolution within two legislative days.However, there are several procedural motions that members of either party could introduce to slow down or stop the process altogether. If those tactics were to fail, and his resolution came to the floor for a vote, it would take a simple majority of the House — 218 votes, when no seats are vacant — to remove McCarthy from his post.But among McCarthy's detractors, passions run deep.Rep. Bob Good, R-Va., who has long wanted McCarthy gone, said the speaker's weekend deal with Democrats to keep the government running without any of the conservative priorities is just another reason he will be voting for the ouster."We got nothing," he said Monday.Still, other far-right members and allies of Gaetz as they fought the spending deal and other issues were less sure. Rep. Andy Ogles, R-Tenn., said his position on the motion was "to be determined."Showing the tough road ahead to win over conservative support for ousting the speaker, Massie said the real history-making moment has been the House working through its regular job of trying to pass spending bills, and he worries this effort will quash all that."If you're asking how I feel, I am sad that this might be the end of that experiment," he said.Democrats were largely treating the moment as another episode in a Republican-led House that has been full of chaotic twists since the start of the year, and declining to say whether they would work to help McCarthy keep his job or vote to oust him."Another day at the show," said Rep. Gregory Meeks, D-N.Y.___AP Congressional Correspondent Lisa Mascaro and writer Stephen Groves contributed to this report.