An anti-gun violence PAC founded by former congresswoman Gabrielle Giffords endorsed two Republican senators on Monday for their record against gun violence.

In an op-ed for CNN on Monday, Giffords and her husband Mark Kelly wrote that Americans for Responsible Solutions would be endorsing Republican Sens. Pat Toomey and Mark Kirk.

"In the wake of the tragedy at Sandy Hook, Republican Sens. Pat Toomey and Mark Kirk broke from the gun lobby and supported a bill to help prevent felons, domestic abusers and the dangerously mentally ill from obtaining firearms at gun shows and online," the two wrote. "This week, they are earning our organization's endorsement."

Toomey of Pennsylvania is currently in a tight battle for reelection against Democratic challenger Katie McGinty. Kirk is fighting against Democratic Rep. Tammy Duckworth in Illinois.

Both Toomey and Kirk voted in 2013 to close background check loopholes following the 2012 December massacre at Sandy Hook Elementary School in Newtown, Conn.

"With the vocal majority of Americans behind us, our movement has reached a tipping point. Our coalition is black and white, Latino and Asian. We are gay and straight. We are gun owners. We are Democrats and Republicans. And we've all had enough with the gun violence that is tearing our communities apart," Giffords and Kelly wrote. They called the 2016 election cycle the year "America found its voice" against guns.