US House of Representatives Speaker Kevin McCarthy is fighting for his political life after a right-wing rebel launched a formal bid to oust him. Responding to the move by Matt Gaetz of Florida, McCarthy posted on social media: "Bring it on." Tensions between the two Republicans boiled over at the weekend after the Speaker passed a bill with the help of Democrats to fund government agencies. No US Speaker has ever been ousted by such a rarely filed motion to vacate. The leadership has two days to bring up the measure for a vote. The Speaker is second in the line of succession for the presidency after the US vice-president. He or she sets the lower house of Congress" legislative priorities, controls committee assignments, and can make or break an American president"s agenda. The deal late on Saturday that averted a government shutdown left out $6bn (£5bn) of funding for Ukraine because Gaetz and other ultraconservatives insist the US has spent too much funding that country"s war with Russia. McCarthy, a California congressman, only became Speaker in January after 15 rounds of voting when he was able to win over a key group of right-wing Republicans. Gaetz, a persistent thorn in McCarthy"s side, was one of the Republicans who repeatedly voted against him at the time - and even until the end the Florida lawmaker abstained from voting. During the political horse-trading before he ultimately won the gavel, McCarthy agreed to a change of rules that would allow any single lawmaker member to call for a vote to oust the Speaker. That paved the way to Monday"s motion to vacate. In a speech on the House floor on Monday, Gaetz accused McCarthy of striking a secret deal with the White House to insert new Ukraine funding into separate legislation. McCarthy has said there is "no side deal on Ukraine". Gaetz, a Trump ally, had already threatened to file the motion in recent weeks, saying he would do so if a short-term government spending bill was passed with help from Democrats. After filing the motion, Gaetz told a crowd of reporters: "Well, 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, and I"m at peace with either result, because the American people deserve to know who governs them." Asked earlier on Monday whether his actions were plunging the institution into turmoil, Gaetz told reporters: "You talk about chaos as if it"s me forcing a few votes and filing a few motions. "Real chaos is when the American people have to go through the austerity that is coming if we continue to have $2 trillion annual deficits." Gaetz told reporters outside the Capitol on Monday night that he would be up for supporting Louisiana Republican Steve Scalise - currently deputy to McCarthy - to succeed the Speaker. Tom McClintock, a California Republican, chastised Gaetz before his floor speech saying he could not "conceive of a more counterproductive and self-destructive course" than removing a Speaker of the same party. McClintock said: "I implore my Republican colleagues to look past their prejudices, their passions, their errors of opinion, their local interests and their selfish views." It would take a simple majority of the House to remove the Speaker in a floor vote. Republicans control the chamber by a narrow 221-212 majority. According to the rules of the chamber, the Speaker is required to keep a list of individuals who could act as a temporary replacement in case the role is ever vacated. If McCarthy were voted out, this list would be made public and the person at the top of it would be named Speaker pro tempore until elections were held in the chamber for a new leader of the majority party in the chamber. Now Democrats must decide if they will step in and vote to help the Speaker keep his job. Democrats are unhappy with McCarthy after he recently approved the launch of a congressional inquiry to see if there is enough evidence to impeach President Joe Biden. But left-wing New York lawmaker Alexandria Ocasio-Cortez told CNN on Sunday her fellow Democrats might be interested in politically bailing out McCarthy if they can extract concessions from him. The rare procedural tool to remove a Speaker has only been used twice in the past century and never successfully. It was last used in 2015 against Speaker John Boehner. The motion to remove him failed but it built enough pressure on Boehner that, unable to unite his caucus, he announced his resignation two months later. Before then it was last used in 1910. — BBC