Republicans censured Friday two lawmakers for joining the investigation into former US President Donald Trump's role in the 2021 US Capitol riots, calling the January 6 attack a "legitimate political discourse."

Liz Cheney and Adam Kinzinger, the lone Republicans on the House select committee probing the January 6 attack, are regarded as adversaries of the ex-President, who retains his grip on the party despite losing the 2020 election.

The 168 Republican National Committee (RNC) members gathered for their winter meeting in Salt Lake City, Utah, and approved a formal censure accusing the pair of behavior that is "destructive to the US House of Representatives, the Republican Party and our republic."

"Legitimate political discourse"

The resolution called the investigation "a Democrat-led persecution of ordinary citizens engaged in legitimate political discourse."

Investigators are probing links between the Trump administration and the former President's supporters who invaded the Capitol on the day it was due to certify Joe Biden as the winner of the 2020 presidential election.

Trump loyalists have been pushing for months for Cheney and Kinzinger to be expelled, particularly as the investigation has closed in on the ex-President's inner circle.

"Hostages" for Trump

Cheney responded to news of the censure motion by reiterating her criticism for Trump.

In a statement, the lawmaker pointed out Thursday that "the leaders of the Republican Party have made themselves willing hostages to a man who admits he tried to overturn a presidential election and suggests he would pardon January 6 defendants, some of whom have been charged with seditious conspiracy."

"I'm a constitutional conservative and I do not recognize those in my party who have abandoned the Constitution to embrace Donald Trump. History will be their judge," she added.