As her colleagues prepared to vote Wednesday on legislation requiring federal background checks for firearms sales and transfers, U.S. Rep. Lucy McBath darted on and off the House floor.

“I was weeping, trying not to weep too much,” the Democrat from Marietta said, “because I recognize that the reason why I ended up here is because of the loss of my own son and the loss of so many other lives like Jordan.”

The chamber's passage of the Bipartisan Background Checks Act was nearly seven years in the making for McBath, who pulled off Georgia's biggest upset win last fall when she defeated incumbent Republican U.S. Rep. Karen Handel in the 6th Congressional District.

McBath first got involved in politics after her teenage son Jordan Davis was fatally shot in a 2012 dispute. She lobbied for gun control legislation across the country as a surrogate for Everytown for Gun Safety and Moms Demand Action for Gun Sense in America, groups that became deeply invested in her congressional race, which she entered after last year's mass shootings in Parkland, Fla.

The background checks bill, which passed the House with the support of eight Republicans and all but two Democrats, was the first legislation McBath signed onto as a new member of Congress. She helped push it through the House Judiciary Committee and worked to block Republicans amendments that she worried would "devalue" the bill.

The legislation “saves as many lives as possible,” McBath said.

Georgia Republicans disagreed.

U.S. Rep. Doug Collins of Gainesville, the top Republican on the Judiciary Committee, said the measure fails to address many of the factors that led to recent mass shootings in Florida and Illinois.

“All this legislation will do is burden law-abiding citizens wishing to exercise their Second Amendment rights, including defending themselves from the gun-toting criminals this bill does nothing to combat,” Collins said in a floor speech Wednesday.

He introduced legislation earlier this week that seeks to increase information-sharing between law enforcement bodies and steepen penalties for stealing guns.

Collins scored a political victory for the GOP on Wednesday when he teed up consideration of an amendment requiring gun sellers to notify federal immigration agents when an immigrant lacking authorization tries to buy a firearm.

The provision was narrowly adopted, embarrassing Democrats and creating a brief ruckus on the House floor. After Democrats passed the underlying bill, gun control advocates cheered from the chamber’s galleries. Wearing an orange scarf, the color of the gun control movement, McBath stood among her Democratic colleagues who applauded back at the advocates.

The legislation is likely dead on arrival in the Republican-controlled Senate, but McBath vowed to press forward on other gun control bills.

“Today was a very big first step,” she said.