Story highlights Rep. Gabby Giffords will address Congress on Monday afternoon

The former congresswoman was planing to campaign with Ralph Northam

(CNN) The Democratic nominee for Virginia governor canceled a series of events Monday with former Rep. Gabby Giffords, a survivor of a mass shooting that left her seriously wounded, and her husband Mark Kelly in the wake of a deadly massacre at a concert in Las Vegas.

Lt. Governor Ralph Northam, who has made stricter gun laws a central plank in his campaign for the commonwealth's top office, canceled a series of events with Giffords and Kelly designed to highlight his differences with the Republican nominee, former George W. Bush adviser Ed Gillespie, on the issue of "the epidemic of gun violence."

Giffords put out a statement on the violence in Las Vegas, saying she was praying for the victims and their families.

"But I am praying for my former colleagues, our elected leaders, too," Giffords said in the statement from her advocacy group Americans for Responsible Solutions. "I am praying they find the courage it will take to make progress on the challenging issue of gun violence. I know they got into politics for the same reason I did -- to make a difference, to get things done. Now is the time to take positive action to keep America safer. Do not wait. The nation is counting on you."