After the Orlando mass shooting, Democrats in Congress are pulling out all the stops to try to force Republicans to pass a new gun-control law. For a few years now, the most prominent voice in this effort — other than President Obama — has been Chris Murphy, a fresh-faced, first-term senator from Connecticut who was thrust into the gun-control debate after the 2012 Sandy Hook Elementary School killings. His decision to lead this filibuster suggests that he's intent on making his case a whole lot more high-profile.

Shortly before lunchtime Wednesday, Murphy launched an old-fashioned filibuster on the Senate floor.

Murphy is filibustering an unrelated spending bill in hopes of forcing Congress to do two things: 1) expand universal background checks and 2) make it illegal for people on the FBI's various suspected terrorism watch lists and no-fly lists to buy guns. The Orlando shooter was originally on an FBI terrorism watch list, then was dropped. But even if Omar Mateen had been on a terrorism watch list the day he bought the guns he used in the shootings, buying them would have been totally legal.

As we wrote Tuesday, getting either of those proposals passed in a Republican-majority Congress is going to be a very heavy lift. Senate Republicans allowed a vote on a terrorism watch list proposal last December after the San Bernardino, Calif., shootings, and it failed. It's unclear whether they'll open up the floor for another vote after Orlando. What Murphy is trying to do is draw attention to the lack of a planned vote — and shame Republicans into giving him one.

There does seem to be room for compromise on preventing people on terrorist watch lists from buying guns: Gun-control advocate groups are making a push with Sen. Pat Toomey (R-Pa.) to introduce legislation on this. And this is happening Wednesday, too:

Clearly, advocates like Murphy sense an opening the likes of which they haven't seen after a mass shooting to get a gun-control bill — even just one — passed. And it makes perfect sense that Murphy is taking the lead on that effort. Here's why:

One state: Connecticut

Gov. Dannel Malloy says he'll sign an order that would require state police to review whether a potential gun buyer is suspected of having ties to terrorism

Murphy's political profile fits a politician who would be fighting for gun-control laws whether or not America was reeling from a mass shooting. He comes from a liberal state that's very supportive of gun laws: Connecticut has the nation's second-strictest gun laws (behind California), according to the Law Center to Prevent Gun Violence, a nonprofit group that supports gun control.

Many of the state's other top officials are outspoken gun-control advocates as well. After the San Bernardino shootings in December, the state's Democratic governor, Dan Malloy, tried to take matters into his own hands to prevent people on the terrorist watch list from buying guns.

Two words: Sandy Hook

Gun control isn't the only issue, of course, that Connecticut voters care about. But to some degree, Murphy had no choice but to make the gun-control fight his No. 1 issue. He was elected to the Senate one month before a mentally unstable man killed 20 first-graders and six adults in a quiet, wealthy suburb in his state.

The 2012 Sandy Hook shootings fundamentally changed how he approaches his job, Murphy has said:

"In a job like this, you're driven to find the issues that move you. And then sometimes, there are issues that find you," Murphy said in his first speech on the Senate floor in April 2013. "When I was elected to the United States Senate last November, I never imagined my maiden speech would be about guns or gun violence. Just like I could never imagine I'd be standing here in the wake of 20 little kids having died in Sandy Hook, or six adults who protected them."

This tweet

This is Murphy's first filibuster on gun control, his staff said. But it's not the first time he's raised eyebrows or grabbed headlines after a mass shooting with a fiery, controversial comment about the need for gun control. (The tweet above was sent after the San Bernardino shooting.)

In a follow-up interview with Vox after that tweet, Murphy said he was angry that several mass shootings have gone by without Congress taking action on gun control. He told his Senate colleagues that he wanted them to "get off their ass" and do something.

Murphy has been beating the drum on that message steadily for three years now: His staff says the senator has delivered 45 speeches on the Senate floor highlighting victims of gun violence.

But lately, he's been getting louder. On New Year's Eve, Murphy went on a tweet-athon of sorts, tweeting every mass shooting since 2015.

After Orlando, Murphy had one of the most strongly worded statements of any Democratic lawmaker:

All of his efforts haven't resulted in any gun-control legislation making its way to the president's desk — the last time Congress passed gun-control legislation was a background-check bill in 1993.

If there ever was a moment that could change that lack of movement, Murphy and his allies clearly think now's it. So expect to hear a lot more from one of Congress's most active voices on gun control.