U.S. House of Representatives Speaker Mike Johnson was reelected to the chamber's top job on Friday by a razor-thin margin that highlighted potential fissures among President-elect Donald Trump's Republicans on Capitol Hill.

Johnson appeared to initially fall short of the majority he needed to retain his job in a roll-call vote that lasted nearly two hours, but two Republican opponents switched their votes to support him after lengthy negotiations, with at least one reporting receiving a call from Trump himself.

Johnson won reelection with 218 votes - the minimum number needed. Republicans control the chamber by a razor-thin 219-215 majority.

Following the vote, Johnson vowed to extend Trump's 2017 tax cuts, which are due to expire this year and roll back regulations.

"We're going to drastically cut back the size and scope of government," he said.

Other big challenges will loom, including addressing the nation's more than $36 trillion in debt, which Congress will need to act on later this year.

Friday's vote was an early test of Republicans' ability to hang together as they advances Trump's agenda of tax cuts and border enforcement. It also tested Trump's clout on Capitol Hill, where a handful of Republicans have shown a willingness to defy him.

House Republicans have been racked by internal divisions over the last two years. Johnson was elevated to speaker after the party ousted his predecessor Kevin McCarthy in the middle of his term.

Members of Congress milled around the chamber for more than half an hour after voting had concluded, where Johnson and his lieutenants could be seen trying to persuade the holdouts.

Representative Keith Self, one of three Republicans to initially vote against Johnson, said he had a "lively" discussion with Trump after doing so. He said he secured a promise that members from the party's right wing would be included in efforts to shape high-profile tax and immigration bills.

"We needed more input from members like myself — not a chairman, not a leadership position — and I think that's what we have done," he told reporters.

Along with Representative Ralph Norman, Self returned to the House floor to vote for Johnson. A lawmaker close to Johnson, speaking on condition of anonymity, said the speaker promised to run the House in a "constructive" way but did not agree to any specific rules changes to win their support.

Representative Thomas Massie, a vocal opponent of Johnson who has long been a thorn in the side of his party's leadership, was the lone Republican to vote against him.

Another six Republicans had initially declined to vote at all before casting ballots for Johnson.

A Reuters photographer captured an image of Representative Marjorie Taylor Greene, who voted for Johnson, talking on her iPhone with the name Susie Wiles - Trump's incoming chief of staff - visible on the screen.

Trump congratulated Johnson following the vote. "Mike will be a Great Speaker, and our Country will be the beneficiary," he wrote on social media.