(CNN) -- Former Rep. Gabrielle Giffords lambasted the 46 senators who voted against an ill-fated bipartisan proposal to expand background checks on firearms sales and vowed to continue her fight for tougher gun laws.
"Speaking is physically difficult for me," Giffords wrote in a New York Times opinion piece published online after the Senate rejected the compromise on Wednesday. "But my feelings are clear: I'm furious. I will not rest until we have righted the wrong these senators have done."
Giffords, a Democrat, was seriously hurt in a 2011 shooting that killed six and wounded 13. She and her husband, Mark Kelly, have been vocal advocates for stricter gun laws since the Sandy Hook Elementary School massacre in Newtown, Connecticut, in December.
Together, the two gun owners formed a nonprofit group, Americans for Responsible Solutions, which lobbied Congress and tried to beat back efforts from the powerful National Rifle Association.
Opponents argued the compromise struck by West Virginia Democrat Joe Manchin and Pennsylvania Republican Pat Toomey to expand background checks to gun shows and Internet sales infringed on Second Amendment rights and wouldn't go far enough to prevent gun violence.
It was offered as an amendment to an underlying package of proposals and needed 60 votes to pass. It received 54.
Giffords stood alongside President Barack Obama at the White House after the Senate vote. Obama sharply criticized lawmakers for failing to pass the amendment, as Giffords nodded her head.
"Some of the senators who voted against the background-check amendments have met with grieving parents whose children were murdered at Sandy Hook, in Newtown," she wrote in the op-ed.
"Some of the senators who voted 'no' have also looked into my eyes as I talked about my experience being shot in the head at point-blank range in suburban Tucson two years ago, and expressed sympathy for the 18 other people shot besides me, six of whom died.
"These senators have heard from their constituents -- who polls show overwhelmingly favored expanding background checks. And still these senators decided to do nothing. Shame on them," Giffords said.