The House Judiciary Committee issued subpoenas Thursday to former Trump campaign manager Corey Lewandowski and ex-White House aide Rick Dearborn.

Both Trump associates were involved in an episode described in special counsel Robert Mueller’s report, in which President Trump tried to use Lewandowski as a backchannel to pressure then-Attorney General Jeff Sessions to limit Mueller’s probe.

With this latest move, the House Judiciary Committee has issued about a half-dozen subpoenas related to Mueller’s probe. Democrats were successful in getting Mueller himself to testify under subpoena and also used subpoenas to secure the partial cooperation of two other Trump White House alumni: former White House Communications Director Hope Hicks and former Deputy White House Counsel Annie Donaldson.

The Trump administration has fought tooth and nail to limit their and others’ compliance with the subpoenas, and the House Judiciary Committee has gone to court to enforce its subpoena of former White House counsel Don McGahn.

The White House is considering invoking executive privilege to block Lewandowski’s testimony even though Lewandowski never worked for the Trump administration, CNN reported Thursday.

Trump, according to Mueller, instructed Lewandowski to direct Sessions to give a speech announcing that the Russia probe would be geared only towards preventing election interference in the future. Lewandowski set up a meeting with Sessions but the attorney general bailed on it, according to the report.

Lewandowski then tried to get Dearborn, who worked for Sessions in the Senate, to pass along the message, which Lewandowski shared in the form of notes he had taken down of Trump’s demands. Dearborn told Mueller he was uncomfortable playing messenger and ultimately did not follow through on Lewandowski’s request.

The House subpoenas demand that Lewandowski and Dearborn appear for testimony on September 17.