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.

“I am glad to have such valuable resources available to help us ensure that this Administration is held accountable to our laws and to the American public,” Nadler said.

Eisen, who helped the Obama administration form notoriously airtight ethical standards as the the White House special counsel for ethics and government reform from 2009 to 2011, has become something of a media magnet in the Trump era.

He has been highly critical of the Trump administration’s ethical standards, speaking out against department heads such as then-Office of Management and Budget Director Mick Mulvaney, former U.N. Ambassador Nikki Haley, and former EPA Administrator Scott Pruitt.

Eisen published at least 74 op-eds in 2018 and has been cited in more than 28,000 news reports since Trump’s inauguration in 2017.

The Judiciary Committee conducted its first oversight hearing last week under the new Democratic majority, asking acting Attorney General Matthew Whitaker about his communications with the White House on a host of issues, including overseeing the Russia investigation.

Watch: A brief overview of Chairman Nadler’s opening questions to Matthew Whitaker