"Everyone should plan on coming tomorrow. We're through for the night," he said.
Reid will file for cloture on the nomination tonight and hopes to reach agreement with Republicans on a final vote tomorrow, a Senate aide told TPM.
Paul was aided on the floor at various times by Sens. Mike Lee (R-UT) Ted Cruz (R-TX), Jerry Moran (R-KS), Saxby Chambliss (R-GA), Marco Rubio (R-FL), Pat Toomey (R-PA), John Cornyn (R-TX) and even one Democrat, Ron Wyden of Oregon.
"I will speak until I can no longer speak," Paul said in his opening remarks. "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 later admitted that Obama himself was not really the cause for his marathon stand in the Senate.
"I frankly don't think he'll be killing people in their homes tonight," he said.
At stake, Paul explained, was the prospect of unchecked power afforded to the executive branch if clear rules governing lethal force within the United States are not established.
The Obama administration has "no intention" of authorizing a drone strike against U.S. citizens on American soil, Attorney General Eric Holder said on Tuesday. However, in a letter obtained by NBC News, Holder acknowledged that "an extraordinary circumstance" might make the option possible.
"It is possible, I suppose, to imagine an extraordinary circumstance in which it would be necessary and appropriate under the Constitution and applicable laws of the United States for the president to authorize the military to use lethal force within the territory of the United States," Holder wrote. "For example, the president could conceivably have no choice but to authorize the military to use such force if necessary to protect the homeland in the circumstances of a catastrophic attack like the ones suffered on Dec. 7, 1941 and Sept. 11, 2001."
Brennan, however, has offered a more straightforward answer. In a letter to Paul obtained by Mother Jones on Tuesday, Brennan affirmed that "the agency I have been nominated to lead does not conduct lethal operations inside the United States -- nor does it have any authority to do so."
The last "talking" filibuster in the Senate occurred in 2010 when Sen. Bernie Sanders (I-VT) rose to speak for more than eight hours against extending Bush-era tax cuts.
As of this article's posting, Paul is still speaking from the floor. Watch it live here.