Sen. Chris MurphyChris MurphySenate heading for late night ahead of ObamaCare repeal showdown Senate releases 'skinny' ObamaCare repeal bill Dems don’t want to help GOP improve repeal bill MORE (D-Conn.) and other Democrats have taken over the Senate floor to call for tougher gun control laws and specifically action on keeping people on terrorist watchlists from buying firearms.

“I'm prepared to stand on this floor and talk about the need for this body to come together on keeping terrorists away from getting guns ... for, frankly, as long as I can, because I know that we can come together on this issue,” Murphy said in beginning the filibuster on Wednesday.

ADVERTISEMENT
Murphy began speaking at about 11:20 a.m., and the filibuster was still going more than 12 hours later.

Other Democrats who joined him included Sens. Richard BlumenthalRichard BlumenthalDem bill would ban controversial pesticide Trump attack puts Sessions in bind Dem leaders amp up calls for bipartisan ObamaCare fixes MORE (Conn.), Joe ManchinJoe ManchinSenate heading for late night ahead of ObamaCare repeal showdown Overnight Healthcare: Four GOP senators threaten to block 'skinny' repeal | Healthcare groups blast skinny repeal | GOP single-payer amendment fails in Senate GOP single-payer amendment fails in Senate MORE (W.Va.), Patrick LeahyPatrick LeahyOvernight Tech: Driverless car bill advances in House | Bezos now world's richest person | Tech groups hail new email privacy bill Senate panel advances measure to protect medical marijuana states Senate panel approves funding boost for Transportation Department MORE (Vt.), Al FrankenAl FrankenOvernight Cybersecurity: Senate sends Russia sanctions bill to Trump | Senators unveil email privacy bill | Russia tried to spy on Macron with Facebook OPINION | Democrats: Time to wish Hillary Clinton good luck and goodbye Franken: ‘Constitutional crisis’ if Trump uses recess appointment to replace Sessions with someone who’ll fire Mueller MORE (Minn.), Cory Booker (N.J.), Bill NelsonBill NelsonGOP senator forces Dems to vote on single payer Gore wishes Mikulski a happy birthday at 'Inconvenient Sequel' premiere Honda recalls 1.2 million cars over battery fires MORE (Fla.), Dick DurbinDick DurbinPassing the DACA legislation will provide relief to children living in fear Dems don’t want to help GOP improve repeal bill Mnuchin: Trump administration examining online sales tax issue MORE (Ill.), Charles SchumerCharles SchumerLive Coverage: Senate votes down 'skinny' ObamaCare repeal Passing the DACA legislation will provide relief to children living in fear OPINION | Trump, there is no better AG than Jeff Sessions — don't lose him MORE (N.Y.), Ben CardinBen CardinBoth sides of the aisle agree — telemedicine is the future Republicans get agreement on Russia, North Korea sanctions Congress can send a powerful message by passing the Israel Anti-Boycott Act MORE (Md.) and Ed MarkeyEd MarkeyOPINION | Shailene Woodley: US should run on renewable energy by 2050 Dems urge 'transparent and inclusive' nuke policy review Senate confirms former Boeing VP as deputy Defense secretary MORE (Mass.).

It also won support from presumptive Democatic presidential nominee Hillary ClintonHillary Rodham ClintonSessions says he doesn't regret recusing himself from Russia probe Judiciary Committee Republicans want a second special counsel: report Fusion GPS: White House trying to smear us on Russia MORE and her rival, Sen. Bernie SandersBernie SandersLive Coverage: Senate votes down 'skinny' ObamaCare repeal Sanders: Senate healthcare fight 'totally bananas' Overnight Defense: Military won't lift transgender ban until Trump sends directions | House passes national security spending | Russian sanctions bill heads to Trump MORE (I-Vt.).

The Senate is currently considering an appropriations bill for the Commerce and Justice departments and science programs. Though no votes are currently scheduled, the senators are blocking any amendments to the bill.

"I don't think we should proceed with debate on amendments to this bill until we have figured out a way to come together," Murphy said, referring to the spending bill.

The Democrats are also technically blocking Majority Leader Mitch McConnellMitch McConnellLawmakers look forward after ObamaCare repeal failure McConnell: 'Time to move on' after healthcare defeat Senate defeats ObamaCare repeal measure MORE (R-Ky.) from ending debate on the legislation, though a spokesman shot down any speculation that the Republican leader would have tried to wrap up work on the spending bill Wednesday.

Democrats have given no indication how long they plan to hold the Senate floor. Chris Harris, a spokesman for Murphy, said Democrats launched the talkathon because the senator will no longer accept “inaction or half measures in the face of continued slaughter.”

The effort comes three days after the deadliest mass shooting in U.S. history. A gunman armed with a Sig Sauer MCX rifle and a handgun on early Sunday killed 49 people at an Orlando nightclub. 

Murphy is well-known for his support for tougher gun control laws. One of America's most shocking gun crimes occurred in his home state in Newtown, where 20 children and six adults were shot to death at Sandy Hook Elementary School.

"I can't tell you how hard it is to look into the eyes of the families of those little boys and girls who were killed in Sandy Hook and tell them that almost four years later we've done nothing, nothing at all," Murphy said. 

Since the Orlando attack, Democrats have put a renewed focused on legislation meant to block the sale of guns to people on terrorist watchlists. 

An effort to move legislation was previously blocked last year. 

Sen. Ben Sasse (Neb.) was the first Republican senator to join Murphy and other Democrats, asking a question about the government's terror watchlists.

"I'm familiar with the terrorist screening database. There are a series of lists that fall from the database, but I don't think there's any such thing as 'the terrorist watchlist,' and I certainly don't understand what due process rights would apply," Sasse said.

Sasse's comment reflects a central problem Republicans have with a proposal from Sen. Dianne FeinsteinDianne FeinsteinLewandowski clashes with ABC host over whether Trump can fire Mueller Overnight Cybersecurity: Senate Judiciary reportedly drops Manafort subpoena | Kushner meets with House Intel | House passes Russia sanctions deal | What to watch at 'hacker summer camp' Manafort agrees to speak with investigators after subpoena MORE (D-Calif.) that would give the attorney general broad authority to block people on watchlists from being able to buy guns or explosives. 

Republicans argue that could deny constitutional rights to Americans who aren’t actually tied to terrorism.

Instead, Sasse and most Republicans support an alternative proposal by Sen. John CornynJohn CornynSenate heading for late night ahead of ObamaCare repeal showdown Two GOP senators back ObamaCare repeal after Ryan call Senate releases 'skinny' ObamaCare repeal bill MORE (R-Texas) that would allow the attorney general to delay suspected terrorists from getting a gun for up to 72 hours while seeking a court order to stop the sale.

Sen. Pat Toomey (R-Pa.), who faces a tough reelection bid, came to the Senate floor urging his colleagues to compromise. 
 
"There's an obvious opportunity here, guys, to work together and find the solution," he said. "What I'm suggesting is let's get to work here." 
 
Toomey on Wednesday criticized the Feinstein measure as "badly flawed." But he also said that Cornyn's proposal, which he previously voted for, likely didn't give enough leeway to the attorney general. 
 
He made the comments after Democratic Senate candidate Katie McGinty, who is hoping to unseat Toomey, pressured the GOP senator to back the Feinstein legislation during a press conference Tuesday. 
 
Wednesday afternoon, Toomey said he planned to introduce a compromise bill Thursday aimed at combining aspects of both the Feinstein and Cornyn proposals.
 
Toomey's legislation would require the attorney general to create a list of "likely terrorists" that could be blocked from buying guns. The list would then be submitted to the Foreign Intelligence Surveillance Court, which would review it annually and remove any Americans inadvertently included, according to a summary of the forthcoming bill from his office.

Updated at 11:35 p.m.