(Image Credit: Charles Dharapak/AP Photo)

Not everyone was so convinced by Rand Paul's near thirteen hour filibuster. Two Republican colleagues called his speech a "political stunt" and the Attorney General send a terse, one-line letter to the Kentucky senator.

Paul built his argument Wednesday around a letter Monday in which Attorney General Eric Holder said the president has the power, however unlikely it would be used, to strike within the U.S. at an American terror suspect.

No more nuance on Thursday after Paul's filibuster. Holder Responded to an additional question from Paul with a single word: "no."

"It has come to my attention that you have now asked an additional question: 'Does the President have the authority to use a weaponized drone to kill an American not engaged in combat on American soil?'" wrote Holder. "The answer to that question is no."

Related: Eric Holder's Letter to Rand Paul

Republican Senators John McCain and Lindsey Graham were more wordy in their attempt to undo questions Paul raised about U.S. foreign policy. They argued that Paul's filibuster "cheapens" the "serious discussion about US policy to the realm of the ridiculous."

"If Mr. Paul wants to be taken seriously, he needs to do more than pull political stunts that fire up impressionable libertarian kids in their college dorms," McCain, R-Ariz., said borrowing quotes from a Wall Street Journal editorial this morning that similarly blasted the Kentucky Republican's filibuster.

Senator Paul is pressing the administration to answer if the White House has the authority to use a drone against a suspected American terrorist on US soil. McCain and Graham's message to their colleagues today was, "calm down, Senator."

Watch: 13 Hours of Filibuster in 3 Minutes

"Mr. Holder is right," McCain said, "even if he doesn't explain the law very well, the US government cannot randomly target American citizens on US soil or anywhere else. I repeat that, the US government cannot randomly target American citizens on US soil or anywhere else."

Sen. Graham said the question Paul is asking is so "ridiculous" it doesn't even deserve an answer.

"This president is not going to use a drone against a noncombatant sitting in a cafe anywhere in the United States, nor will future presidents, because if they do, they will have committed an act of murder," Graham, R-SC., said, "noncombatants under the law of war are protected, not subject to being killed randomly. So to suggest that the president won't answer that question somehow legitimizes that the drone program is going to result in being used against anybody in this room having a cup of coffee, to me, cheapens the debate."

McCain said he does not disagree that there needs to be more debate, discussion and legislation on enemy combatants and drones. But the imagery, drawn up by the filibuster yesterday, was a "stretch of the imagination," that is not helpful to the overall conversation, he said.

"I think disservice to a lot Americans by making them think that somehow they're in danger from their government," McCain said, "they're not." Senator Graham held up an oversized poster on the floor to drive this point home - in big letters written:

"Number of Americans Killed in the US:

"-By al-Qaeda: 2,958

"-By Drones: 0?

Then came a lecture for the other Republicans, like Senate Minority Leader Mitch McConnell, who joined Senator Paul on the floor in his filibuster last night.

"I saw colleagues who know better come to the floor and voice some of this same concern, which is totally unfounded," McCain said.

"I saw colleagues of mine who know better come to the floor and voice the same concern," Senator Graham said, "To my Republican colleagues, I don't remember any of you coming down here suggesting that President Bush was going to kill anybody with a drone."