The House select committee investigating the US Capitol insurrection is planning for former Justice Department official Jeffrey Clark to testify next Friday — teeing him up to be the first Trump administration official to comply with a subpoena for an interview with the panel, two sources familiar with the committee’s inquiry told CNN.

Clark’s testimony could be a major step forward for Democrats as they attempt to determine what former President Donald Trump, Republican members of Congress and his advisers did and said behind closed doors about overturning the results of the 2020 election before January 6.

CNN has also learned that Alyssa Farah, former director of strategic communications in the Trump White House and assistant to the president, has voluntarily met with Republicans on the House select committee and provided information in several meetings, according sources familiar with the matter. There are two Republicans on the committee — Vice Chair Liz Cheney and Rep. Adam Kinzinger.