After initially planning a statehouse run, McBath switched races last spring, challenging then- Congresswoman Karen Handel, R-Roswell, shortly after a gunman killed 17 students at Marjory Stoneman Douglas High School in Parkland, Fla.

"Either you are completely about the business of saving people's lives or you're not," McBath said in an interview last spring. "There's no in between."

Gun control groups quickly endorsed McBath, including her former employers Everytown for Gun Safety and Moms Demand Action for Gun Sense in America. Several of those groups aided her campaign with millions in outside spending, much of it going toward advertising aimed at bolstering McBath's name identification and attacking Handel.

Many of McBath’s former colleagues from Everytown and Moms Demand Action attended Tuesday’s press conference and swarmed the new congresswoman following the event, as did several of the Parkland students.

McBath is one of five Democrats and five Republicans to be listed as original cosponsors of the legislation, which the chamber’s Democratic leaders have vowed to make a priority in the months ahead. It was given the low bill number H.R. 8 to symbolize the issue’s importance to the party, as well as the eighth anniversary of the Tucson shooting that killed six and nearly claimed Giffords’ life.

While Democrats have touted the public popularity of expanded background checks, the legislation is likely to be stonewalled in the GOP-controlled Senate. President Donald Trump has also vowed to safeguard Second Amendment rights, although his administration did move to ban bump stocks last month.

Top Republicans swiftly rejected the proposal.

“While I share my colleagues’ conviction that Congress must find effective ways to prevent violence, promote public safety, and protect life, today’s bill is not a solution on any of these fronts,” said U.S. Rep. Doug Collins of Gainesville, the top Republican on the House Judiciary Committee. “Recent shootings reflect failures not of existing policy—background checks are already in place and working across the board—but failures in its implementation.”

The influential gun rights group the National Rifle Association previously voiced opposition to similar background check legislation.

"So-called universal background checks will never be universal because criminals do not comply with the law," an NRA spokeswoman told the Associated Press.

McBath has also advocated for raising the minimum age for purchasing a gun to 21, overturning concealed carry reciprocity measures and enacting “red flag” laws, which permit families and police to petition courts to take firearms away from people who pose a danger to themselves or others.

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