Rep. Elijah Cummings threatened Tuesday to hold former White House adviser Carl Kline in contempt of Congress for defying a subpoena ordering him to testify about his role allegedly covering up wrongdoing in the Trump administration’s White House security clearance process.

President Donald Trump’s White House counsel directed Kline in a letter earlier this week not to comply with the subpoena. Kline did not appear for his scheduled deposition.

“It appears that the President believes that the Constitution does not apply to his White House, that he may order officials at will to violate their legal obligations, and that he may obstruct attempts by Congress to conduct oversight,” Cummings, who chairs the House Committee on Oversight and Reform, said in a statement Tuesday.

The Maryland Democrat, whose committee is investigating allegations of impropriety and nepotism in the White House’s security clearance process, said he will consult with House counsel and other members on his panel about scheduling a vote on contempt.

“I hope that Mr. Kline, in close consultation with his personal attorney, will carefully review his legal obligations, reconsider his refusal to appear, and begin cooperating with the Committee’s investigation,” Cummings said.