The House committee examining the Jan. 6 attack on the United States Capitol Building has taken a major step forward in its investigation into the role any members of Congress played in the incident. To figure this out, the committee has issued subpoenas to House Minority Leader Kevin McCarthy, (R-Calif.), and four other Republican lawmakers.

On Thursday, the committee announced that it would be subpoenaing McCarthy, Reps. Jim Jordan, (R-Ohio), Scott Perry, (R-Pa.), Andy Biggs, (R-Ariz.), and Mo Brooks, (R-Ala.) for testimony. Several of these members, including McCarthy, were previously requested to voluntarily provide information to the committee, but each refused.

To subpoena sitting members of Congress as witnesses to a congressional investigation is entering uncharted territory where the legality of the move is both untested and unclear. However, committee chairman Rep. Bennie Thompson, (D-Miss.), said that his panel was compelled to seek the Republicans’ testimony in light of evidence they held information important to the investigation.

"The Select Committee has learned that several of our colleagues have information relevant to our investigation into the attack on January 6th and the events leading up to it," Thompson said in a statement.

"Regrettably, the individuals receiving subpoenas today have refused and we’re forced to take this step to help ensure the committee uncovers facts concerning January 6th," he continued.

Each of the congressmen has been connected in some way to either efforts to overturn the 2020 presidential election or for communications with former President Donald Trump on the day of the Capitol Riot.

Last month, it was revealed that McCarthy privately told GOP counterparts that he would ask Trump to resign and fumed over his incitement of the mob to assault the Capitol. In the riot’s wake, McCarthy said that Trump bore a degree of responsibility for it, but ultimately sought to mend fences with the ex-president within weeks of the attack.

Like McCarthy, Jordan was a close Trump ally during his presidency and he was also reportedly in touch with him on Jan. 6. Jordan was also in attendance at meetings with Trump allies at the White House to discuss efforts to overturn the election.

Biggs reportedly attended these same meetings and also played a role in planning the Stop The Steal rally that preceded the attack on the Capitol. Because of his role in planning the rally, Biggs reportedly attempted to secure a preemptive presidential pardon from Trump, according to CNN.

Brooks came into focus following his attendance at the Stop the Steal rally as well. His testimony took on more urgency after he claimed Trump asked him to try and overturn the election following Trump’s rescinding of his endorsement for Brooks in Alabama’s upcoming election for the U.S. Senate.

Finally, Perry reportedly worked to help install Jeffrey Clarke, a Justice Department official who was open to Trump’s claims of election fraud.

None of these claims have been substantiated in countless lawsuits and investigations, but belief in the “Big Lie” that the election was stolen from Trump has become something of a prerequisite for earning Trump’s support for many Republican officials.