(CNN) - Sen. Rand Paul ended his day-long filibuster at 12:38 a.m. Thursday, almost 13 hours after he began speaking. The Kentucky Republican tried to stall a confirmation vote on CIA Director nominee John Brennan.
He took to the Senate floor at 11:47 a.m. ET.
And as a snow storm swirled outside Wednesday in the nation's capital, Paul started his own Twitter hash tag that encapsulated his hours-long stand-off on Capitol Hill: #filiblizzard.
The Kentucky senator, known for his libertarian leanings, has sharply questioned the Obama administration's use of drones against American citizens overseas and vowed to speak Wednesday until he received more answers from the government about its policies. Brennan is considered one of the main architects of the drone program.
Paul in particular wants to know whether the government believes it has the authority to carry out drone attacks against American citizens on U.S. soil. He took issue with Attorney General Eric 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's disturbed by the idea that an American citizen would lose his or her rights while within the country's borders.
"I rise today to begin to filibuster John Brennan's nomination for the CIA," Paul said. "I will speak until I can no longer speak. I will speak as long as it takes."
Wearing a dark grey suit and a red tie, Paul detailed his argument, staring intently at the Senate leaders presiding over the floor. The first-term senator stood with a thick binder full of notes in front of him–but he rarely looked at them.
Paul, who hasn't ruled out a 2016 presidential bid, said he doesn't consider President Barack Obama is a "bad person," but he said the president is also "not a judge."
"He's a politician," Paul said. "He was elected by a majority, but the majority doesn't get to decide who we execute. We have a process for deciding this. We have courts for deciding this, to allow one man to accuse you in secret, you never get notified you have been accused."
He continued: "Your notification is the buzz of the propellers on the drone as it flies overhead in the seconds before you're killed."
Holder narrowed the list of those possible extraordinary circumstances Wednesday. In testimony before the Senate Judiciary Committee, Sen. Ted Cruz, R-Texas, pressed Holder 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 letter to Paul, he called the possibility of domestic drone strikes "entirely hypothetical."
Paul, who was elected in 2010 with wide tea party support, said he understands that due process doesn't apply to combat zones overseas.
"But when people say, 'Oh, the battlefield's come to America' and 'the battlefield's everywhere,' 'the war is limitless in time and scope,' be worried, because your rights will not exist if you call America a battlefield for all time," the senator said.
The term filibuster–which originates from a Dutch word meaning "pirate"–caught fire in the 1850s when it became a popular method to hold up a bill or vote on the Senate floor.
Nearly seven hours in, Paul's filibuster is hardly a record. In the 1930s, Sen. Huey Long from Louisiana was known for reciting Shakespeare and reading recipes on the Senate floor when he filibustered. He once held the floor for 15 hours.
Former Sen. Strom Thurmond of South Carolina holds the record. He famously filibustered for 24 hours and 18 minutes against the Civil Rights Act of 1957.
In recent history, independent Sen. Bernie Sanders of Vermont held the floor in 2010–though technically not through a filibuster–to protest a tax-cut deal for eight hours and 37 minutes.
Three hours in, Paul showed little signs of fatigue. He frequently shifted weight from one leg to the other and rested his hands on the desk from time to time. But a full glass of water sat untouched in front of him, and Paul rarely let go of his eye contact with his Senate colleagues.
After about six hours, however, Paul's level of fervor began to fade. The pace of his speech slowed down and he read more often from notes. Around 6:15 p.m. ET, he chowed down a snack in between sentences, talking with his mouth full.
For most of the time, Paul squarely placed blame on the president for what he perceived a dangerous precedent in federal law. The Kentucky senator was quick to make comparisons between President Obama and candidate Obama.
"I think it's also safe to say that Barack Obama of 2007 would be right down here with me arguing against this drone strike program if he were in the Senate," he said. "It amazes and disappoints me how much he has actually changed from what he once stood for."
Obama said there's something "contagious" about the office of presidency and cited the famous quote by John Dalberg-Acton.
"It's not just power corrupts, but that 'absolute power corrupts absolutely'," Paul said. "I think people can become intoxicated with power. I don't know if that's the explanation for President Obama's about-face. He was one, when he was in this body believed, in some restraint."
But Paul did not endure the filibuster by himself. At three hours and 10 minutes, he began sharing his time with other Republican senators, Mike Lee of Utah, Ted Cruz of Texas, Jerry Moran of Kansas, Marco Rubio of Florida, Saxby Chambliss of Georgia, John Cornyn of Texas, John Barrasso of Wyoming, John Thune of South Dakota, and Pat Toomey of Pennsylvania, who each weighed in with questions and their own commentary.
"I would note that your standing here today like a modern Mr. Smith Goes to Washington must surely be making Jimmy Stewart smile," Cruz said to Paul. His appearance represented his first time to speak on the Senate floor. "And my only regret is that there are not 99 of your colleagues here today standing with you."
Cruz noted that Wednesday marked the anniversary of the fall of the Alamo in San Antonio, Texas. Comparing the fight to Paul's effort on the Senate floor, Cruz said "Texans are proud" to see Paul (a native Texan) standing up "for liberty."
He then read a famous letter–perhaps in a move to kill time–from William Barret Travis in 1836, asking for more back-up at the Alamo.
Cruz, talking to Paul, said he hopes the "glorious letter give(s) you encouragement and sustenance on this 177th anniversary on the Alamo."
At just over four hours, the filibuster took an interesting twist when a Democratic senator, Ron Wyden of Oregon, came to the floor to assist and make the stand-off a bipartisan effort.
It's important to note that the drone controversy is one of the few issues where the far right and the far left sync up. While Wyden said he wants to make his point about the targeted killing of Americans by drones, he said he will still vote for Brennan at the end of the day. He did so in the Senate Intelligence Committee.
"Senator Paul and I agree that this nomination also provides a very important opportunity for the United States Senate to consider the government's rules and policies on the targeted killings of Americans," he said.
At just around five hours into the filibuster, Senate Majority Leader Harry Reid came to the floor to gauge whether or not the Senate could hold a vote on Brennan Wednesday night.
He tried to limit the remaining time for debate to 90 minutes, but Paul objected, saying he wants answers from Holder that clarify his remarks on drones Wednesday morning.
Reid said he can't speak for the administration and canceled his request, meaning there would be no full vote on Brennan Wednesday.
The filibuster had its light-hearted moments, as well. When Rubio stepped up to join the filibuster, he had some words of wisdom for Paul.
"I know you've been here awhile. Let me give you some advice - keep some water nearby. Trust me," Rubio joked, poking fun at his now-famous sip of water during the middle of his Republican response to the president's State of the Union address last month.
Around 7:30 p.m. ET, Cruz returned to the floor to read aloud tweets about Paul's filibuster.
"I think the technical term for what the Twitterverse is doing right now is called 'blowing up'," Cruz said, highlighting the slogan–"Stand with Rand"–that's spreading online.
In the ninth hour, Lee again took over the spotlight so Paul could have a break. While the senator from Utah was speaking, Paul chatted with House members and paced back and forth in between the Senate desks. Since beginning the talking filibuster shortly before noon, he has not sat down or taken a bathroom break.
Well into the 11th hour, Rubio returned and at one point started quoting the musical artist Jay-Z.
A short time later, Senate Minority Leader Mitch McConnell came to the floor to express his support for the effort.
"At whatever point we get to a cloture vote to extend debate on the nomination of Brennan, it is my view that cloture should not be invoked. This is a controversial nominee. Should cloture be invoked, I intend to oppose the nomination and congratulate my colleague from Kentucky for this extraordinary effort," McConnell said.
And with midnight quickly approaching, Paul’s support from his colleagues only seemed to be intensifying. Republican members of Congress began gathering in the Senate chamber in solidarity. And at 11:47 pm Republican National Committee Chairman Reince Priebus tweeted an all-call to Republican senators who weren't already on the floor:
Paul continued to talk so he wouldn’t have to relinquish the floor, but he did not have to stay on the floor to keep his filibuster going. Although he was drawing attention to his objections to the administration's drone policy, senators are not required to be on the floor to block a vote, unlike previous times.
So what would have happened if Paul had kept going?
At some point, Reid was expected to make a parliamentary move that would start the clock ticking for a vote to break the filibuster. Sixty votes would have been needed to break the filibuster, and as Paul himself has acknowledged, he didn’t have the votes to succeed.
After that procedural vote to break the filibuster, Paul still could have dragged things out—-the rule allows an additional 30 hours of debate–into the weekend, before there would be a final vote to confirm Brennan.
But, Paul instead yielded the floor early Thursday morning, allowing Senator Dick Durbin to file cloture to end debate on Brennan’s nomination.
- CNN's Terry Frieden, Dana Bash, Rachel Streitfeld and Alison Harding contributed to this report.