Democratic Senator Chris Murphy is leading a filibuster aimed at demanding congressional action on gun control. Politico reports:

The day began in earnest when Murphy (D-Conn.) launched a talking filibuster on the Senate floor — which was quickly joined by fellow Democrats — in an effort to pressure Republicans to accept legislation that would deny suspected terrorists from purchasing firearms and require universal background checks.

The Senate is debating a spending bill that Democrats hope to offer gun amendments to, but Murphy said that the Senate should “not proceed with debate on amendments to this bill until we have figured out a way to come together on, at the very least, two simple ideas.”

“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 continued on the Senate floor on Wednesday, after he first started his filibuster at about 11:20 a.m.

Sen. Murphy also explained the rationale behind the filibuster on Twitter:

I'm speaking on the Senate floor to honor the victims of the Orlando attack & demand the Senate address gun violence. #Enough

— Chris Murphy (@ChrisMurphyCT) June 15, 2016

I am prepared to stand on the Senate floor and talk about the need to prevent gun violence for as long as I can. I've had #Enough

— Chris Murphy (@ChrisMurphyCT) June 15, 2016

After every act of grave violence, the American people have called for action. But Congress has failed them. #Enough pic.twitter.com/J6OdQeGuU9

— Chris Murphy (@ChrisMurphyCT) June 15, 2016

There is common ground on this issue. The majority of Americans want us to take action to end gun violence. We can come together. #Enough

— Chris Murphy (@ChrisMurphyCT) June 15, 2016

Hillary Clinton offered her support to Murphy’s effort:

Some fights are too important to stay silent. Preventing gun violence is one of them. Stand strong @ChrisMurphyCT. https://t.co/LEl7iSLCgF

— Hillary Clinton (@HillaryClinton) June 15, 2016

Politico reports there was talk behind the scenes between Republican John Cornyn and Democrat Dianne Feinstein Tuesday, but by Wednesday Sen. Feinstein was telling reporters, “I don’t think that’s gonna work out.”

NBC News published this time-lapse video of the first several hours of Murphy’s filibuster: