TUCSON, Ariz Representative Gabrielle Giffords, gravely wounded a year ago in a deadly Tucson shooting spree, submitted her resignation from Congress on Wednesday to focus on her recovery.
"The only way I ever served my district in Congress was by giving 100 percent. This past year that's what I have given to my recovery," Giffords said in letters to House of Representatives Speaker John Boehner and Arizona Governor Jan Brewer.
"This past year my colleagues and staff have worked to make sure my constituents were represented in Congress. But if I can't return, my district deserves to elect a U.S. Representative who can give 100 percent to the job," she added.
Her resignation will be effective at the end of the day on Wednesday.
The three-term Arizona Democrat was holding a meet-and-greet event at a Tucson supermarket on January 8 last year when a gunman opened fire.
Six people were killed, including a 9-year-old girl and a federal judge, and 12 others were wounded including Giffords, who was shot through the head.
She has since received intensive therapy at a Texas hospital to recover from the injury that left her with broken speech and a marked limp.
Giffords announced she would step down on Sunday, and has since carried out final visits and duties in the swing district where she won reelection by only 4,000 votes in 2010, a year that saw many Democrats lose seats.
On Tuesday night, she received a standing ovation from colleagues and a hug and kiss from President Barack Obama in an emotional appearance at the State of the Union address in Washington.
Giffords cast a last vote in the House on Wednesday for legislation she crafted with Republican colleague Rep. Jeff Flake to levy new penalties on traffickers using small, low-flying aircraft to smuggle drugs across the U. S. border from Mexico.
In a rare display of bipartisanship, the vote on the Giffords legislation was 408 to 0.
A centrist seen is a rising Democratic star in Congress, Giffords pledged on Wednesday to return to public service in the future.
"Every day, I am working hard. I will recover and will return, and we will work together again, for Arizona and for all Americans," she wrote.
Jared Loughner, a college dropout, was charged with first-degree murder, the attempted assassination of Giffords and other crimes stemming from the shooting. He pleaded not guilty and was found mentally unfit to stand trial.