After hearing only silence from Mueller on the FBI’s use of domestic surveillance drones eight days past the junior Kentucky senator’s July 1 deadline, Paul threatened to block the Senate confirmation of James Comey as the new head of the Federal Bureau of Investigation.

Firing off a letter to Mueller on Tuesday, Paul said, “Unfortunately, I have not received any answers to my questions, and I have not been informed as to when I should expect a reply.”

On Tuesday, the Senate Judiciary Committee questioned Comey — who is President Obama’s top pick for the position — over his positions on torture, the Boston Marathon Bombings and the federal government’s surveillance apparatus.

Paul notes in his letter that the full Senate could take up consideration of Comey’s confirmation later in the month.