Story highlights So far, the White House has turned more than 20,000 pages of material to Mueller's office

Mueller's office has collected millions of documents

Washington (CNN) President Donald Trump's lawyers released an overview Thursday of what they say is an "unprecedented" attempt to cooperate with the special counsel and congressional Russia probes.

Twenty White House staffers, including eight from the White House counsel's office, have sat for voluntary interviews with investigators, the overview said. Those interviews at Robert Mueller's office include White House counsel Don McGahn, communications director Hope Hicks, senior policy adviser Stephen Miller and former chief of staff Reince Priebus, according to previous CNN reports.

Another 17 campaign employees and 11 other individuals affiliated with the Trump campaign gave interviews to Mueller's office or during congressional investigations.

The public accounting comes as Trump's attorneys negotiate the terms of the President's appearance before the special counsel.

Three former campaign advisers have been hit with charges in the Mueller probe, as well as one senior White House staff member. As Mueller's team has investigated potential Russian collusion with Trump's campaign, it has scheduled individuals for voluntary interviews with the FBI and prosecutors, and compelled some people to testify before a federal grand jury.

Read More