While not privy to the details of the complaint, House Intelligence Committee Chairman Adam Schiff wrote in a letter to the Office of the Director of National Intelligence last week about the whistleblower.

He wrote that from what he has gleaned, he believes "the serious misconduct at issue involves the President of the United States and/or other senior White House or Administration officials."

Schiff announced Wednesday that Director of National Intelligence Joseph Maguire will appear at 9 a.m. on September 26.

The California Democrat also announced that the intelligence community inspector general will brief the House committee Thursday behind closed doors about how it handled the whistleblower complaint.