Former Obama administration ethics czar Norm Eisen has been hired by the House Judiciary Committee as it probes the Department of Justice and other aspects of the Trump administration and seeks to shield the special counsel investigation into Russian election interference.

Chairman Jerrold Nadler of New York has said that protecting the Special Counsel Robert S. Mueller III’s investigation into the 2016 election, including possible ties between the Trump campaign team and Russia, is the committee’s No. 1 priority.

Eisen has been retained on a consulting basis along with Barry Berke, a leading white-collar criminal defense attorney, as special oversight counsels to the majority Democratic staff as they conduct their inquiries into Trump’s Justice Department.

“This is a critical time in our Nation’s history,” Nadler said in a statement Tuesday.

The chairman said in the statement that Trump is accused of “numerous” instances of “corruption and obstruction,” and indicated that the committee will be gathering evidence about those claims with help from Eisen and Berke.