FBI Director Robert Mueller testifies before the U.S. Senate Judiciary Committee on Wednesday, June 19, 2013, in Washington D.C., where he said drones are "seldom used" on U.S. soil for their maximum capability. (Saul Loeb/AFP/Getty Images)

More than two weeks have passed since Sen. Rand Paul, R-Ky., requested "prompt" answers to questions about the FBI's use of drones within the United States, but he is still waiting for a response.

It's unclear why the FBI did not immediately provide answers to Paul's 11 questions, but the delay could conceivably morph into an unwelcome spectacle for the Obama administration.

Paul inquired about the domestic use of drones in a June 20 letter to FBI Director Robert Mueller, after the director told the Senate Intelligence Committee his agency was using the unmanned devices without clear guidelines.

Paul asked Mueller to explain how long the FBI has been using drones, how many drones the FBI has, whether or not FBI drones would ever be armed, why they are used, what policies guide their use and what has been done with the information they collect.

Moira Bagley, Paul's communications director, told U.S. News Friday that the FBI has not provided answers to the questions. She declined to speculate if Paul would filibuster the confirmation hearing of James Comey to replace Mueller as FBI director in response to the delay.

Comey, a Republican, was nominated by President Barack Obama in June and is widely expected to be easily confirmed.

In June Bagley said it was "too early to tell" if Paul would filibuster Comey's nomination. Now, Bagley says, she would need to confer with other Paul staffers to learn what steps might be taken to wring out answers.

In March Paul stood on the Senate floor for 13 hours to filibuster the nomination of John Brennan to lead the CIA after Attorney General Eric Holder failed to definitively rule out using drones to kill people within the U.S.

"I am disturbed by the revelation that the FBI has unilaterally decided to begin using drone surveillance technology without a governance policy, and thus without the requisite assurances that the constitutional rights of Americans are being protected," Paul said in his letter to Mueller. "As such, I am requesting your prompt answers."

Mueller's disclosure about domestic drone use by the FBI alarmed even the administration's most stalwart supporters, including Sen. Dianne Feinstein, D-Calif, who called drones "the greatest threat to the privacy of Americans."

A spokesperson for the FBI director could not be reached by U.S. News for comment. "This is a weekday, a regular work day," an FBI phone operator said. "I don't have any idea why they wouldn't be here."

UPDATE:

The FBI is "still in the process of responding" to Paul’s letter, spokesman Paul Bresson tells U.S. News.