Senate Republican Leader Mitch McConnell is praising his Kentucky colleague Rand Paul’s nearly 13-hour filibuster, and is now opposing President Obama's nominee to run the Central Intelligence Agency.Paul held up the confirmation of John Brennan for CIA director using an old-school filibuster. He continually asked for the administration to promise they will not use armed unmanned aircrafts to kill American citizens on U.S. soil.In a letter sent Monday, Attorney General Eric Holder told Paul the administration had "no intention" to use drones on suspected terrorists in the U.S., but could do so in "extraordinary circumstances."As the filibuster gained national attention and bipartisan support, McConnell and a number of GOP senators joined Paul's effort last night.Speaking on the Senate floor Thursday, McConnell says the White House has a responsibility to answer Paul’s questions before the nomination goes forward."The United States military no more has the right to kill a U.S. citizen on U.S. soil who is not a combatant with an armed unmanned aerial vehicle than it does with an M-16. The technology is beside the point. It simply doesn’t have that right and the administration should simply answer the question," he says.Despite McConnell's vocal support, two veteran GOP lawmakers took to the Senate floor denouncing Paul's 13-hour speech as "offensive" and saying it cheapened the debate.From The Washington Post: (John) McCain and (Lindsey) Graham said they support the president’s right to use deadly force — including drones — against U.S. citizens on U.S. soil who are engaged in terrorism, when there aren’t other options available. (SNIP) “I don’t worry about [drones killing Americans],” Graham said. “Here’s what I worry about: that al-Qaeda has killed 2,958 of us and is going to add to the total if we let our guard down. And I will do everything in my power to protect this president — who I disagree with a lot — and future presidents in having an ill-informed Congress take over the legitimate authority under the Constitution and the laws of this land to be the Commander in Chief on behalf of all of us.”Meanwhile, McConnell announced he will not support Brennan’s nomination to lead the intelligence agency and urged his caucus to vote against ending the debate."After four years of working within the White House, confronting difficult policy matters on a daily basis, and having attempted to defend the administration’s policies—sometimes publicly, sometimes to the media, and occasionally to the U.S. Senate, I question whether Mr. Brennan can detach himself from those experiences. For that reason, I will oppose his nomination," says McConnell.This means that it will take a 60-vote majority to end the debate. Senate Democrats reportedly believe they have enough support to clear that hurdle and are pushing for a vote on Brennan's nomination as early as Thursday afternoon.Observers also question if McConnell's move to oppose the Brennan nomination is a political calculation that was made after the success of Paul's filibuster.During the early hours of the speech, several Tea Party activists and conservative pundits noted McConnell's absence and demanded he join Paul on the Senate floor.UPDATE:White House Press Secretary Jay Carney told reporters on Thursday the attorney general has sent a letter to Paul, who asked if President Obama has the authority to use a drone against a citizen domestically."The answer to that question is no," Carney said.Aides say Paul has not yet received Attorney General Holder's letter.UPDATE II:Here is a copy of the succinct letter.