Carolyn McCarthy ran for Congress for one reason: gun control. For her, the issue was personal.

After the Newton, Conn., elementary school shooting last Friday, the New York Democratic congresswoman from Long Island has threatened to "embarrass" President Obama if he doesn't take action on gun control.

"I was just giving the White House a heads up that the gloves are off on my side, and I was going to do everything I possibly could," McCarthy told Politico last week after the Newtown shooting - the fourth such gun tragedy since Obama took office in 2009.

"If that meant embarrassing everybody, that's what I would do," she said. "As a mother, and as someone whose family was changed forever by an act of gun violence, I know all too well what the families in Connecticut are going through right now," McCarthy said Sunday on CBS' "Sunday Morning." "We owe it to those families, and to our own children, to do something about our nation's problem with gun violence."

If anyone in Congress can understand the personal aftermath of Newtown, it's McCarthy. On Dec. 7, 1993, Colin Ferguson opened fire on a crowded Long Island Rail Road train, killing six people, including McCarthy's husband. Her son was severely wounded in the gunfire.

She launched her political career not only out of that rampage but out of a political fight over gun control that followed in 1997.

McCarthy, a registered Republican who had worked as a nurse, began speaking out in favor of gun control after the Long Island Rail Road shooting. In 1996, her congressman, Rep. Dan Frisa, a Republican, announced that he planned to vote to repeal the federal Assault Weapons Ban. He was mounting his re-election campaign at the same time that McCarthy was advocating for tougher gun laws.

"I told him, 'You're our congressman in this area where the Long Island Rail Road massacre happened, and you're telling me that you're still going to vote to repeal it? Are you not working for us? Are you not our public servant?'" McCarthy said as Frisa moved forward to vote in favor of repealing the Assault Weapons Ban, along with other House Republicans in March 1996. "And he said he had to stand up for the Second Amendment."

McCarthy testified in favor of keeping the ban at a House hearing called by then-Rep. Charles Schumer, D-N.Y., now the state's senior senator. She also vowed to "do everything I could to make sure he didn't win re-election" if Frisa, who had received donations from the National Rifle Association, voted to repeal the ban. Frisa did vote to repeal the ban, but House Republicans failed to eliminate it, facing opposition in the Senate and from President l Clinton.

McCarthy decided to challenge Frisa herself to represent New York's Fourth District, as a Democrat.

"If I get mad enough, my Irish up enough, yeah, I'd do it," McCarthy said, explaining her decision.

McCarthy won, but at her victory party, she was somber.

"All we wanted was to make something good come out of a horrible situation," McCarthy said in her victory speech, The New York Times reported at the time. "I certainly did beat the person I wanted to beat. But I've also beaten the NRA."

Since then, McCarthy has pushed for gun-control measures as her signature issue in Congress, including the National Instant Check System Improvement Amendments Act of 2007, which strengthened background checks by including mental-health records in the federal background-check system for gun purchasers. President Bush signed it into law almost seven months after the 2007 Virginia Tech shooting, with backing from the NRA.

That was the first major gun-control legislation Congress had passed in more than 12 years, the Brady Campaign to Prevent Gun Violence said at the time. With the Assault Weapons Ban having expired in 2004, and without any significant gun laws passed since McCarthy's bill became law in 2008, McCarthy's Irish is up again, and with a handful of pro-gun lawmakers signaling willingness to restrict access to guns, some momentum seems to be gathering behind her long crusade.