Senate Democrats launched a filibuster on Wednesday (June 15) to fight for gun control measures in the wake of last weekend's mass shooting in Orlando.

"This is a different moment today than it was at the end of last week," Connecticut senator Chris Murphy, who initiated the filibuster, said. "There is a newfound imperative for this body to find a way to come together and take action."

Fellow Connecticut senator Richard Blumenthal quickly joined Murphy on the floor. Both men represent Newtown, the town where a mass shooting claimed 26 lives in 2012. Senators Cory Booker of New Jersey and Chuck Schumer of New York also spoke up. Others were reportedly signing up for speaking slots as late as 10:30 pm.

Murphy launched the filibuster during senate's consideration of the Commerce, Justice and Science Appropriations Act, which provides funding for the Justice Department, among other things. Democrats already planned to introduce two gun control amendments to the bill, but were moved to further action by the tragedy in Orlando.

Murphy hopes the filibuster will force agreement on gun control before the vote proceeds.

"I'm going to remain on this floor until we get some signal, some sign that we can come together on these two measures, that we can get a path forward on addressing this epidemic in a meaningful, bipartisan way," Murphy said.

The "two measures" refer to the Democrat's two amendments: one to require universal background checks, and one to prevent those on the terrorist watch list from purchasing guns. While the filibuster continued, Democrats and Republicans debated two means of addressing the latter.

Many Republican senators support a measure backed by the National Rifle Association, which would allow judges to clear those on the terrorist watch list to buy a gun. Democrats prefer to give only the Department of Justice this authority. 

This is an ongoing story, and will be updated as more details become available.

UPDATE 4:22p.m.: Elizabeth Warren speaks.

Senator Elizabeth Warren added her voice to the filibuster Wednesday afternoon, voicing her support for gun control amendments proposed by the Democrats.

“Our nation is awash in the weapons of murder,” she said from the Senate floor, “and there are many things we can do to address that.”

First, the Massachusetts senator suggested banning “Rambo-style” assault rifles. Second, she pushed to close the gun show loophole, and third, she asked senators to keep those on the terrorist watch list from buying guns. She concluded by pushing her fellow senators to act — quickly.

"We can build a stronger, more united America, and we can begin right here in the Untied States senate," Warren said. "We can being right now."

UPDATE 5:27p.m.: Female senators bring the fire.

Following Warren’s powerful testimony, senators Jeanne Shaheen, Kirsten Gillibrand and Claire McCaskill took their turns at the podium.

All three women voiced their support for the Democrats’ proposed amendments. Gillibrand took it a step further, urging the Senate to allow the Centers for Disease Control and Prevention to study gun violence.

"Is this slaughter not a wake up call? Is it not enough to act?" Gillibrand asked. "Where is our spine?"

McCaskill echoed this call, asking her fellow senators why they let fear of the NRA keep them from taking action.

"Is it the NRA that is single-handedly stopping this?" she asked. "…Because the majority of constituents in this country want universal background checks."

UPDATE 7:02a.m.: Filibuster has concluded.

The Democratic filibuster ended early Thursday morning, after almost 15 straight hours of discussion on gun control legislation.

Formally yielding the floor at 2:11a.m., Murphy announced that a vote would be held on the two Democratic amendments to the Commerce, Justice and Science Appropriations Act: One to require background checks for gun purchases at shows and online, and another to prevent those on the terrorist watch list from acquiring guns. Democratic senators — 38 of which participated in the filibuster — celebrated the victory. But they recognized the battle was far from won.

"Thank you for following," Booker tweeted to supporters during the filibuster. "Let's now win these votes."

This may be easier said than done, as Democrats and Republicans have yet to come to an agreement on how to regulate those on the terrorist watch list. A version of Democratic senator Diane Feinstein’s proposal — to bar gun sales to those on the watch list — failed to pass a Senate vote in December. Many Republicans still stand by the NRA-backed version of the law, which would allow the government to block suspected terrorist for only 72 hours.

"My guess is we're back to square one," an aide told Politico after the filibuster.

But Murphy remained positive after his marathon stint on the floor. He ended his remarks with a tribute to Dylan Hockley and Anne Marie Murphy, victims of the 2012 mass shooting in Sandy Hook.

"For those of us that represent Connecticut, the failure of this body to do anything, anything at all in the face of that continued slaughter isn't just painful to us, it's unconscionable," Murphy said.