Republican leader Kevin McCarthy and three other Republican politicians should face ethics investigations for their refusal to comply with congressional subpoenas, the House January 6 committee said on Monday in the culmination of a months-long standoff over their testimony.

The committee had issued subpoenas in May for the testimony of Mr McCarthy — who is vying to become House speaker in January — as well as Jim Jordan of Ohio, Scott Perry of Pennsylvania, and Andy Biggs of Arizona, saying all had crucial information to share about the January 6 attack and the actions of former president Donald Trump.

But all of them defied the order for testimony and documents. The January 6 committee on Monday acknowledged that sending referrals to the House Ethics Committee was a major step, but said their defiance could not go unanswered.

Another GOP member who ignored a committee subpoena, Rep Mo Brooks of Alabama who is leaving Congress after this year, was not cited by the panel.

“This was a significant step, but it was one that was warranted by the certain volume of information these members possessed that was relevant to the Select Committee’s investigation, as well as the centrality of their efforts to President Trump’s multi-part plan to remain in power,” the committee wrote in explaining the referrals.

It will ultimately be up to the House Ethics panel, which is evenly decided between the parties, to investigate and decide on any punishment.

The committee, which is responsible for investigating allegations of misconduct by members, has authority under the chamber’s rules to subpoena members for testimony or documents, and members are required to comply.

Russell Dye, a spokesperson for Mr Jordan, called the decision “another partisan and politician stunt” by the committee.

Jay Ostrich, a spokesperson for Mr Perry, dismissed the committee’s move as “more games from a petulant and soon-to-be defunct kangaroo court desperate for revenge and struggling to get out from under the weight of its own irrelevance”.

Requests for comment from Mr McCarthy and Mr Biggs were not immediately returned.

The January 6 committee also appealed directly to the Justice Department in their final report, suggesting that the testimony of Mr McCarthy, Mr Jordan and other Republicans in Trump’s orbit could be of importance to the ongoing federal investigations, including special counsel Jack Smith’s probe into the Capitol riot and Mr Trump’s actions.

The testimony of the politicians, the panel suggested, could be obtained “via grand jury subpoena or otherwise.”

The panel had sought testimony from Mr McCarthy, who has acknowledged he spoke with Mr Trump on January 6 as the president’s supporters were outside the Capitol and violently forcing their way into the building.

At the time, the he said he believed Mr Trump bore responsibility for what had happened at the Capitol. But Mr McCarthy later changed his tone, visiting Mr Trump in Florida and rallying House Republicans to vote against investigations of the attack.

The committee had also subpoenaed Mr Jordan, Mr Perry, Mr Biggs and Mr Brooks, who attended meetings at the White House before January 6 as Mr Trump and his aides worked to overturn his 2020 election defeat.

Mr Perry spoke to the White House about replacing acting Attorney General Jeffrey Rosen with an official who was more sympathetic to Mr Trump’s false claims of voter fraud, while Mr Biggs was involved in plans to bring protesters to Washington and pressuring state officials to overturn the legitimate election results, according to the panel.

Mr Jordan, the top Republican on the House Judiciary Committee, was in contact with Mr Trump on January 6 and also involved in strategising how to overturn the election.

Mr Brooks, who has since become critical of Mr Trump, was the only member not referred to the Ethics Committee. He had spoken alongside the former president at the massive rally in front of the White House the morning of January 6, telling supporters to “start taking down names and kicking ass” before hundreds of them broke into the Capitol.