The House select committee investigating the January 6 attack on the Capitol has issued unprecedented subpoenas to five Republican members of Congress, seeking to compel their cooperation with the inquiry into Donald Trump’s efforts to overturn the 2020 election.

The select committee empowered the chairman, Bennie Thompson, to move ahead with subpoenas to the House minority leader, Kevin McCarthy, Jim Jordan of Ohio, Scott Perry of Pennsylvania, Andy Biggs of Arizona and Mo Brooks of Alabama.

The five congressmen flatly refused to accept invitations to provide voluntary assistance to the investigation, sources said.

Thompson said: “Before we hold our hearings next month, we wished to provide members the opportunity to discuss these matters with the committee voluntarily. 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.”

The subpoena letters indicate that the select committee is seeking testimony from the five House Republicans about some of the most sensitive details about Trump’s unlawful efforts to overturn the election, including their contacts with Trump.

The Guardian reported earlier this week that the panel was moving closer to issuing subpoenas to Republicans in Congress, appalled at their refusal to assist in any way despite prima facie connections to the events of 6 January.

What changed for members of the committee, according to sources familiar with internal deliberations, was that they could no longer ignore what appeared to be deep involvement in Trump’s unlawful schemes to overturn the 2020 election results.

After the announcement, McCarthy told reporters that “I have not seen a subpoena” and repeated his previous attacks on the committee. “They’re not conducting a legitimate investigation,” he said. “Seems as though they just want to go after their political opponents.” Meanwhile, Perry called the investigation a “charade”.

The voluntary cooperation letters outlined in damning detail the reasons that the select committee wanted to depose the five Republicans, as House investigators prepare to wrap up their work ahead of public hearings in June.

From McCarthy, the select committee said it wanted to learn more about his communications with Trump before, during and after January 6, including a conversation in which the former president admitted he was partly at fault for the Capitol attack.

The panel is keenly interested in what McCarthy believes prompted Trump to make such an admission, the sources said, since it could offer evidence that the former president had a guilty conscience for a possible future justice department criminal investigation.

From Biggs, the former chairman of the ultra-conservative House Freedom Caucus, the select committee said it wanted to learn more about meetings House Republicans had with Trump at the White House in the days and weeks leading up to January 6.

The panel is focusing on a 21 December 2020 meeting that took place in the Oval Office with Trump, the letter indicated, since those attending appeared to strategize ways to unlawfully delay or stop Joe Biden’s certification from taking place and return Trump to power.

The select committee also wants to depose Jordan to learn more about that meeting with Trump and other communications he had with the former president, his letter said.

In the letter to Perry, the select committee said he was directly involved with efforts to corrupt the justice department and install a pro-Trump DoJ official, Jeffrey Clark, as acting attorney general if he opened investigations into baseless claims of election fraud.

The panel also subpoenaed Brooks since he spoke at the “Save America” rally at the Ellipse that preceded the Capitol attack, where he notably wore a bulletproof vest under his shirt, and has spoken publicly about Trump pressuring him to “rescind” his election loss.

One notable and unexplained exception from the list was congressman Ronny Jackson, Trump’s former White House doctor, whose name surfaced in text messages among members of the Oath Keepers militia group that stormed the Capitol, some of whom were indicted for seditious conspiracy.

Biggs’ possible contacts with far-right activist Ali Alexander are of special interest to the investigation, sources said.

The committee is trying to untangle claims by Alexander that he “schemed up putting maximum pressure on Congress while they were voting” with Brooks, Biggs and Paul Gosar, another Arizona Republican, and his testimony that he spoke to Biggs’s staff and the congressman himself.

Alexander obtained a permit to hold a rally at the Capitol on 6 January but that event never took place. Alexander was instead filmed going up the Capitol steps in a “stack” formation with members of the Oath Keepers militia.

Thompson said the panel wanted to ask Biggs about his efforts to pressure legislators to create “alternate” slates of electors for Trump in states he lost, as well as an alleged request he made to Trump for a pardon in the days after the Capitol attack.