Senate Minority Leader Chuck Schumer (D-NY) is demanding that the Justice Department inspector general open an investigation into potential “unlawful or improper communications” between Acting Attorney General Matthew Whitaker and White House officials.

“I am particularly concerned about whether Mr. Whitaker may have shared with the White House, or could share in his new role, confidential grand jury or investigative information from the Special Counsel investigation or any criminal investigation,” Schumer wrote in a Tuesday letter to Justice Department inspector general Michael Horowitz.

Whitaker, a former Iowa tight end and one-time hot tub marketer, has refused to recuse himself from overseeing the Mueller investigation, despite the fact that he criticized the probe while working as a conservative activist and talking head on cable TV.

Schumer, in what could be an oblique reference to an obstruction of justice investigation into Trump, wrote that leaking information to the White House – “especially to a target or subject in the investigation” – could “implicate criminal contempt of court, obstruction of justice” or violate DOJ policy on keeping discussions about ongoing criminal cases away from the Oval Office.

The list of questions that Schumer provided for the inspector general adds more interesting fodder for what Whitaker may have been up to when he was Jeff Sessions’ chief of staff.

Schumer asked the inspector general to investigate whether Whitaker, before becoming acting attorney general, obtained “access to confidential grand jury or investigative information related to the Special Counsel investigation?”

The letter also asked the inspector general to find out if Whitaker “provided any assurance” to the White House that any subpoenas or other investigative moves would be blocked.

Federal vacancy statutes limit Whitaker’s appointment to 210 days from his initial Nov. 7 appointment. A group of Senate Democrats filed a lawsuit on Monday arguing that Whitaker’s appointment is unconstitutional.