Two Freedom Caucus Republicans asked the Justice Department’s inspector general Monday to investigate allegations that Deputy Attorney General Rod Rosenstein threatened to subpoena the email and phone records of House Intelligence Committee staff.

Freedom Caucus Chairman Mark Meadows of North Carolina and caucus co-founder Jim Jordan of Ohio made the request in a letter to Inspector General Michael Horowitz, which alleges Rosenstein threatened the subpoenas in a tense January meeting about oversight requests from committee Republicans.

The Freedom Caucus leaders said two unidentified witnesses of the incident can provide documentation and sworn statements attesting to the encounter, which they say concerned oversight requests the committee sent to the department.

“This notion Mr. Rosenstein threatened to use his official investigative powers as Deputy Attorney General to retaliate against rank-and-file staff members for sending written oversight requests raises concerns he has abused his authority in the context of this investigation,” they write in the letter.

Filing a resolution to impeach Rosenstein “is an option being considered, as it has been for weeks,” a Meadows spokesman said.

The Justice Department did not immediately respond to requests for comment Monday night.

The staffers’ allegations against Rosenstein were first raised in an article published by Fox News.

The letter is the latest in a series of efforts by House Republicans to aggressively question the Justice Department’s handling of investigations into Russian interference in the 2016 election and possible coordination with members of the Trump campaign.

Rosenstein denied the allegations after Jordan raised the issue to directly in an oversight hearing last month. Rosenstein said the Fox News report was “mistaken,” that he did not threaten to subpoena emails or calls, and “there’s no way to subpoena phone calls.”

The Freedom Caucus is a hardline conservative group of three dozen House members.

Lindsey McPherson contributed to this report.