WASHINGTON

EVEN as he fights the N.R.A., Chris Murphy understands that guns are in the DNA.

The very junior senator from Connecticut, the father of two small boys, long ago decided not to allow any toy guns in the house or violent video games or even Teenage Mutant Ninja Turtles.

“We have lots of trucks and trains,” he said, pausing before adding about his 4-year-old: “But you know it doesn’t matter. My son still picks up anything that’s shaped like a gun, like a certain construction of Legos, and uses it as a gun. But he knows that when I leave home I’m working on getting guns away from the bad guys, so he’s a little more sensitive now.”

At 39, Murphy is the youngest member of the Senate. He’s tall, attractive and crisp in blue shirt and blue striped tie. He was a blank slate and back-bench congressman before Newtown, known mostly for tweeting about Justin Bieber and surviving a more than $40 million onslaught by the WWE’s Linda McMahon in the 2012 campaign.

Gun safety was not his cause; his district didn’t include any big cities. But he was transformed by the massacre in serene Newtown of Sandy Hook’s “beautiful babies,” in Joe Biden’s words.

“I got to the firehouse a couple hours after the shooting,” Murphy says, his voice thrumming with emotion as he recalled being with parents while they learned the unthinkable. “I sometimes wish I didn’t see some of the things I saw. It’s not that in the past I’ve been disconnected from the issues I’ve worked on. But this is the first one in which I’ve felt an emotional imperative to deliver. These parents are my contemporaries. I’ve got two little boys at home just younger than the ones that were killed.”

The new senator, cramped in the basement, has not even moved into a permanent office. Yet he has been thrust to the forefront of the Sisyphean battle for gun safety in a Congress where some N.R.A. puppets are still arguing to allow felons to conceal guns, and to let imbalanced veterans and people who have been locked up in mental institutions bear arms too. It’s the same Congress where the campaign of one lawmaker, the Texas Republican Steve Stockman, tweeted a new bumper sticker: “If babies had guns they wouldn’t be aborted.”

Murphy said it was hard, flying down on Air Force One with the trepidatious Sandy Hook families, to explain that they would be lobbying to get a vote on a vote. “They thought they were coming down here to argue for a ban on high-capacity magazines and universal background checks, and we told them that they were coming to argue to avert a filibuster and allow us to debate,” he said. “And that was really heartbreaking and deflating for some of them. But they rose to the occasion, and it was wonderful to see them at the end of the trip feeling like they had made a difference.”

On Wednesday, Murphy made his maiden speech on the Senate floor, telling the story of Anne Marie Murphy, a Sandy Hook special education teacher who died with an autistic student, 6-year-old Dylan Hockley, enfolded tightly in her arms, trying in vain to protect him.

“That morning, I read it aloud in my office by myself and I cried,” he recalled. “I made it through, barely, on the floor. I’m not an overly emotional guy, but I’ve been as emotional as I’ve ever been for the past four months.”

He has been debunking the N.R.A. with reports and mocking it with tweets, including one making fun of Barry Manilow’s being on the N.R.A. Enemies’ List (a list that has since been removed from the group’s Web site). He petitioned Nascar — unsuccessfully — to drop the N.R.A. as the sponsor of this weekend’s race. And he wants the Hollywood ratings arbiters to “pay as much attention to violence as they do to sex.”
“Gun ownership has dramatically dropped over the last 20 years, so now it’s about selling a larger number of more expensive weapons to a smaller number of customers,” the senator said. “The N.R.A., doing the bidding of the industry, ratchets up paranoia about government so that those people will go out and buy more guns.”

His mother, a Republican who has also morphed into a militant for stricter gun control, sends him several e-mails a day urging him on — or apologizing for being so hard on his former colleagues in the State Legislature as she lobbies them to come around on the issue.
One Connecticut rifle manufacturer is leaving the state because of its strict new gun restrictions. “If we made our schools safer at the expense of a handful of jobs,” Murphy said coolly, “I think that’s a trade-off we have to make.”

How did he feel about the Manchin-Toomey background check compromise?

“It was both insufficient and sufficient,” he replied. “When my 4-year-old asks for two scoops of ice cream and he gets one and a half, he still eats the one and a half. You’re not going to disenfranchise the N.R.A. overnight. I think ultimately we will get the assault weapons ban because I don’t think this is the last time a man will walk into a crowded place with an AR-15.”

Senator Murphy left to go to Connecticut for the weekend, where he would debrief the families. “And I’ve had to carve out time to spend with my boys,” he said solemnly. “That’s more important to me now than it was prior to Dec. 14.”