The US House of Representatives has elected Republican Mike Johnson, a conservative with little leadership experience, as its Speaker after a turbulent three weeks that left the rudderless chamber unable to respond to the Middle East crisis or carry out any of its basic duties.

The 220 to 209 party-line vote elevated Johnson to a leadership post that has been vacant since Kevin McCarthy was ousted on October 3 by a small group of his fellow Republicans.

“We want our allies around the world to know that this body of lawmakers are reporting again to our duty stations,” Johnson, 51, said shortly after winning the Speaker’s gavel on Wednesday (Thursday AEDT).

He said he would soon call up legislation to signal support for Israel, which has stepped up its bombings of Gaza following a cross-border killing and kidnapping spree by Hamas militants early this month.

First elected in 2016, Johnson will be the least experienced House Speaker in decades. He is best known as the author of an unsuccessful appeal by 126 House Republicans to get the Supreme Court to overturn election results in states that Donald Trump had lost in the 2020 presidential election.

Johnson, of Louisiana, declined to answer a question about that effort shortly after his nomination on Tuesday night, while other Republicans booed and heckled the reporter who asked it.

In a letter to colleagues, Johnson has vowed to advance overdue spending legislation and ensure that the US government does not shut down when current funding expires on November 17.

In his speech, he said he would prioritise border security and would establish a bipartisan commission to examine ways to tackle the $US33 trillion ($A52 trillion) national debt.

He will also have to respond to Democratic President Joe Biden’s $US106 billion spending request for aid to Israel, Ukraine and US border security. While his Republicans broadly support funding for Israel and the US border, they are divided over further support for Ukraine.

The uncertainty has helped to push up the US government’s borrowing costs. The government posted a record $US1.7 trillion deficit for the most recent fiscal year, in part due to higher interest payments.

Democrats blasted Johnson’s conservative stances on social issues like abortion and gay marriage, as well as his efforts to overturn the 2020 election.

Republicans narrowly control the House by a 221-212 margin, leaving them with little room for error on controversial votes. Their divisions were on display over the past few weeks, as they nominated three candidates for speaker – Steve Scalise, Jim Jordan and Tom Emmer – but were unable to provide the 217 votes needed to win the Speaker’s gavel.

– AAP