Sen. Rand Paul's (R-Ky.) talking filibuster against John Brennan's nomination as CIA director ended after nearly early 13 hours.

“I would go for another 12 hours to try to break Strom Thurmond’s record, but I’ve discovered that there are some limits to filibustering and I’m going to have to go take care of one of those in a few minutes here," Paul said as he ended his marathon speech.

Paul began speaking just before noon Wednesday on the Senate floor in opposition to Brennan's nomination, saying that he planned to speak "for the next few hours" in a rare talking filibuster.

Watch live video from the Senate floor below:

Paul, who strongly opposes the Brennan nomination and the Obama administration's use of unmanned aerial drones, became the first senator to make use of the procedural tactic in more than two years and the first to do so since the Senate approved a bipartisan rules reform package in January.

Paul has since been joined in his symbolic effort by Republican Sens. Mike Lee (Utah), Ted Cruz (Tex.), Jerry Moran (Kan.), Marco Rubio (Fla.), Saxby Chambliss (Ga.) and Pat Toomey (Pa.). He has also gotten some bipartisan support from Democratic Sen. Ron Wyden (Ore.). Sen. Mark Kirk (R-Ill.) brought Paul an apple and a thermos of tea -- a possible reference to the film Mr. Smith Goes to Washington, in which Jimmy Stewart brings out similar provisions.  

"I will speak until I can no longer speak," Paul said. "I will speak as long as it takes, until the alarm is sounded from coast to coast that our Constitution is important, that your rights to trial by jury are precious, that no American should be killed by a drone on American soil without first being charged with a crime, without first being found to be guilty by a court."

Paul began his filibuster at 11:47 a.m. Eastern time. At the start of the 1 p.m. hour, he was the only senator on the floor. Just 30 people watched from the Senate gallery above while a few security guards, stenographers and Senate pages held their appointed spots on the floor. In the rafters, a man responsible for operating the Senate television cameras was seen reading a newspaper.

But after more than three hours, Paul got some help and the filibuster began to gain steam. Lee joined the filibuster at 2:57 p.m. and Cruz at 3:08 p.m. Wyden jumped in in the filibuster's fifth hour, at 3:53 p.m.

Paul’s comments from the Senate floor come after he’s raised objections in recent weeks. Paul first threatened to filibuster the Brennan nomination in late February, when he sent a letter to administration officials asking whether the U.S. government would ever use a drone strike to kill an American on U.S. soil.

Attorney General Eric H. Holder Jr. responded to Paul’s inquiry Monday, saying the administration has “no intention” of carrying out drone strikes on suspected terrorists in the United States, but could use them in response to “an extraordinary circumstance” such as a major terrorist attack.

Paul called Holder’s refusal to rule out drone strikes within the United States “more than frightening.”

On Wednesday, Paul elaborated on his concerns: "When I asked the president, can you kill an American on American soil, it should have been an easy answer. It's an easy question. It should have been a resounding, an unequivocal, 'No.' The president's response? He hasn't killed anyone yet. We're supposed to be comforted by that."

Wyden agreed in part with Paul's filibuster, even as he was mostly satisfied with Holder's response: “I want it understood that I have great respect for this effort to really ask these kinds of questions … And Sen. Paul has certainly been digging into these issues in great detail."

At 4:45 p.m., Senate Majority Leader Harry Reid (D-Nev.) took to the floor to see if Paul would say when he will end his filibuster so that senators could prepare for a vote to end debate and bring the nomination to a vote.

Paul dug in, saying he would be happy to end it, but only "if the president or the attorney general will clarify that they will not kill Americans on American soil."

Reid informed senators before leaving: "Everyone should plan on coming tomorrow. We're through for the night."

Just after 7 p.m., Paul asked for Democrats to consent to vote on a non-binding resolution that would express opposition to the drone killings of American citizens on American soil. Sen. Dick Durbin (D-Ill.) rejected it, promising a committee hearing on drone strikes instead, and Paul continued his filibuster.

Paul noted that he has voted for Obama’s previous Cabinet nominees, including Secretary of State John Kerry and Secretary of Defense Chuck Hagel, and suggested that his cause was not partisan.

“I have allowed the president to pick his political appointees," Paul said. "But I will not sit quietly and let him shred the Constitution. ... I would be here if it were a Republican president doing this. Really the great irony of this is that President Obama’s opinion on this is an extension of George Bush’s opinion."

Paul also said that he was "alarmed" at the lack of definition over who can be targeted by drone strikes. He suggested that many college campuses in the 1960s were full of people who might have been considered enemies of the state.

"Are you going to drop ... a Hellfire missile on Jane Fonda?" Paul asked.

Brennan has gained the support of some Republican senators, even as others want to hold up his nomination in hopes of getting more answers from the White House on drones and also the deaths of four Americans in Benghazi, Libya. His nomination easily cleared the Senate Intelligence Committee this week, suggesting he would have the 60 votes required to end Paul's filibuster and bring the nomination to a vote.

Any senator can opt to hold the floor to speak on any matter, but the practice of speaking for hours on end is rare. That goes double in the modern-day Senate, where the chamber's rules are used more often to block legislation or to hold show votes on trivial matters.

Paul's talking filibuster is the first conducted by a senator since December 2010, when Sen. Bernie Sanders (I-Vt.) held the Senate floor for more than eight hours in opposition to Obama's proposed tax-cut plan.

The longest filibuster in the Senate was Sen. Strom Thurmond's (D-S.C.) 24-hour filibuster against the 1957 Civil Rights Act. (Thurmond later became a Republican.) Two other senators — Sens. Alphonse D'Amato (R-N.Y.) and Wayne Morse (I-Ore.) — have also filibustered for more than 20 hours.

Cruz, shortly after joining the filibuster, compared Paul to another famous filibusterer, Jimmy Stewart's character in the movie "Mr. Smith Goes to Washington."

"You're standing here like a modern-day 'Mr. Smith Goes to Washington,' " Cruz said. "You must surely be making Jimmy Stewart smile."

The Kentucky senator was allowed to yield to the other like-minded conservatives for "a question," but there are no rules mandating the form of the question. So, for example, Cruz and Lee delivered long speeches themselves in opposition to the drone program, sometimes actually stopping to ask Paul a question, other times going on for extended speechifying.

The oddity of the day was the chamber's far-right corner -- literally -- seized control of the body. The most junior Republicans occupy seats in the far-right corner and most junior Democrats in the far-left corner, with the more tenured senators getting seats closer toward the middle.

So, as newcomers Paul, Lee, Rubio and Cruz spoke out against the CIA nominee, they did so from contiguous desks in the deep right corner of the room, as the rest of the chamber was vacant.

As the person leading the filibuster, Paul was forbidden from ever leaving the floor, lest he lose control of the debate.

Updated at 7:19 p.m. Paul Kane contributed to this report.

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