(CNN) - Sen. Rand Paul ended his quest Thursday to block a vote on the nomination of John Brennan to be CIA director after he received an answer from the Obama administration about his question on drones.
Paul's decision to back down cleared the way for a final Senate vote this afternoon, and the chamber confirmed Brennan in a 63-34 vote that crossed party lines.
In a letter to Paul Thursday afternoon, Attorney General Eric Holder said that the president does not have the authority to use a drone to kill an American not engaged in combat on U.S. soil.
"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?' The answer to that question is no," the three-sentence letter stated.
In an interview with CNN's Dana Bash, Paul said he was satisfied with the response.
"I'm quite happy with the answer," the Republican senator from Kentucky said. "I'm disappointed it took a month and a half and a root canal to get it, but we did get the answer."
Bringing attention to his question, Paul led a nearly 13-hour filibuster on the Senate floor Wednesday, blocking the confirmation process for Brennan to move forward.
The senator hit back at criticism that he was simply trying to be an obstructionist. Paul argued, rather, he was trying to get information.
"You use the leverage of your position and the procedures up here, I think, for a greater good," he said. "This is an example, I think, of trying to do something you really strongly believe in."
At 1:15 p.m. ET, White House Press Secretary Jay Carney said the letter was sent to Paul "within the last half hour or so."
But the senator did not see the letter until shortly after 2 p.m. ET.
Elaborating further on the administration's position, Carney said Thursday that the technology of a drone strike does not change the law.
"The president swore an oath to uphold the Constitution, and he is bound by the law, whether the lethal force in question is a drone strike or a gun shot, the law and the constitution apply in the same way," he said.
Asked by CNN National Political Correspondent Jim Acosta whether the president could use such force to prevent at attack on U.S. soil, Carney said "you can make sort of wild hypotheticals but that doesn't, they don't change the law."
"It is certainly the case that the president, in part of his oath to the Constitution, to uphold the Constitution, is sworn to protect the United States," he said. "And in event like an attack like Pearl Harbor or an attack like 9/11–obviously the president has the constitutional authority to take action to prevent those kinds of attacks, but that has nothing to do with the technology used to prevent those attacks."
Earlier this week, Paul took issue with Holder's recent admission, in which he said he could envision a scenario where a drone strike would, in fact, be ordered against Americans on U.S. soil.
While Holder said it's never been done before and he could only see it in an extraordinary circumstance, Paul said he was disturbed by the idea that an American citizen would lose his or her rights while within the country's borders.
Holder narrowed the list of those possible extraordinary circumstances Wednesday. In testimony before the Senate Judiciary Committee, Sen. Ted Cruz, R-Texas, pressed Holder on whether he believed it would be constitutional to target an American terror suspect "sitting at a cafe" if the suspect didn't pose an imminent threat.
After first saying it would be "inappropriate," Holder attempted to clarify his answer by giving a firm "no."
But he also said the government has no intention of carrying out drone strikes inside the United States. Echoing what he said in a separate letter to Paul sent earlier this week, he called the possibility of domestic drone strikes "entirely hypothetical."