Speaker Ryan backs Nunes in battle with Justice Department over documents

Nunes has threatened to try to hold Attorney General Jeff Sessions in contempt.

"We clearly expect the administration to honor our document requests," Ryan said at a news conference Tuesday.

Nunes first threatened to hold Sessions in contempt of Congress - a rare step for a Republican chairman to take against a Republican attorney general - on Sunday in an interview with "Fox and Friends," after the Justice Department said in a letter that it would not provide documents in response to his request "regarding a specific individual."

"Disclosure of responsive information to such requests can risk severe consequences, including potential loss of human lives, damage to relationships with valued international partners, compromise of ongoing criminal investigations, and interference with intelligence activities," assistant attorney general Stephen Boyd said in a letter to Nunes.

On Monday, Nunes doubled down on the threat and questioned the Justice Department's assertion that the White House also opposed providing Congress with the requested information.

"I just don’t believe that the White House does not want to comply with a subpoena from Congress that is pertinent to our investigation that we’ve had ongoing for a long time," said Nunes, adding that he had not spoken to the president about the issue but had sent the White House a letter about his request.