Johnson elected speaker in US House of Reps vote

US House of Representatives Speaker Mike Johnson has been re-elected to the chamber's top job in a lengthy vote that highlighted persistent divisions among president-elect Donald Trump's Republicans on Capitol Hill.

Johnson appeared to initially fall short of the majority he would need to retain his job in an hour-long roll-call vote but two Republican opponents switched their votes to support him after more than half an hour of negotiations.

He won re-election with 218 votes - the minimum number needed - against 215 opposed.

Republicans control the chamber by a razor-thin 219-215 majority.

Republican representatives Thomas Massie, Ralph Norman and Keith Self originally all voted for candidates that were not Johnson.

Norman and Self subsequently changed their votes to support Johnson.

The vote was an early test of the party's ability to hang together as it 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 already 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 while Johnson and his lieutenants could be seen trying to persuade the holdouts.

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.

The House went through 15 rounds of voting over four days in 2023 before electing McCarthy speaker.

The mild-mannered Louisiana representative, 52, was vaulted from obscurity into one of Washington DC's most powerful jobs during three weeks of turmoil in October 2023 when Republicans forced out McCarthy and struggled to agree on a successor.

The conservative Christian lawyer emerged as a consensus pick but has since struggled to keep his party unified.

He has sought to build a close relationship with Trump, who endorsed him on Monday following weeks of uncertainty.

"A win for Mike today will be a big win for the Republican Party," Trump posted online on Friday.

Trump returns to the White House on Inauguration Day, January 20.

In a role that is second in line to the presidency after the vice president, Johnson will have a big job ahead.

In addition to taking on Trump's sweeping legislative agenda, Congress will need to address the country's debt ceiling later this year.

With the federal government already more than $US36 trillion ($A58 trillion) in debt, many congressional Republicans are expected to demand significant spending cuts.

Congress is scheduled to meet on Monday to certify Trump's presidential election victory.

with AP