The House committee investigating the events around the 6 January attack on the US Capitol has asked the congressman and close Trump ally Jim Jordan to make an appearance before the panel.

Jordan is a conservative Republican from Ohio who is seen as a close confidant of the former US president.

“We write to seek your voluntary co-operation in advancing our investigation,” the committee said in a letter to Jordan, asking for an appearance early in January.

The letter revealed that the panel was seeking to ask Jordan about the role Trump might have played as the attack unfolded. The mob of pro-Trump supporters had stormed the Capitol in a bid to stop the certification of Joe Biden’s victory in the 2020 election.

“We understand that you had at least one and possibly multiple communications with President Trump on January 6th. We would like to discuss each such communication with you in detail,” it said.

The letter also revealed its interests were wider than the attack itself and included the activities of Trump allies and aides holed up in a Washington hotel. “We also wish to inquire about any communications you had on January 5th or 6th with those in the Willard War Room, the Trump legal team, White House personnel or others involved in organizing or planning the actions and strategies for January 6th,” the letter read.

The request is the second by the nine-member panel this week to go after a sitting Republican congressman and launches a new phase for the panel.

Scott Perry, a Pennsylvania Republican, has also been asked by the panel to provide documents and sit for an interview. But on Tuesday Perry said he would not comply with the panel.

Perry’s refusal to appear set up a potentially fraught battle if the panel decides to subpoena him and he – like other Trump allies – decides to ignore that, too. Jordan is widely expected to decline to cooperate.

Jordan, a staunch Trump ally, has been identified as the Republican lawmaker who sent a message to Trump’s chief of staff Mark Meadows the day before the Capitol attack outlining a plan to stop Biden from reaching the White House.

The panel has been looking at numerous messages sent to Meadows, many of which were urging Trump to call off a mob of his supporters as they ransacked the Capitol building.

Jordan forwarded a text message to Meadows on 5 January, one of the congressman’s aides has confirmed, containing details of the plot to block Biden.

The message was sent to Jordan by Joseph Schmitz, a former US defense department inspector general, who outlined a “draft proposal” to pressure the then vice-president, Mike Pence, to refuse to certify audited election returns on 6 January.

A portion of the message was revealed by the Democratic committee member and congressman Adam Schiff. It read: “On January 6, 2021, Vice-President Mike Pence, as president of the Senate, should call out all electoral votes that he believes are unconstitutional as no electoral votes at all.”