Gabrielle Giffords resigns from Congress "I will recover and will return," Giffords said in a letter that a friend and colleague read Teary-eyed legislators from both parties gave her a standing ovation House Minority Leader Nancy Pelosi called Giffords the "brightest star among us" House Majority Leader Eric Cantor called her "an inspiration to us and to all Americans" (CNN) -- Rep. Gabrielle Giffords, who moved the nation with an improbable comeback after a gunman shot her in the head last year, formally resigned Wednesday in an emotional appearance in the U.S. House of Representatives. "I will recover and will return," the Arizona Democrat said in a letter read aloud by her friend and colleague, Rep. Debbie Wasserman Schultz, who fought back tears as she read. A standing ovation roared across the House Chamber for Giffords, who served three terms. Teary eyed legislators from both parties applauded Giffords as she submitted her letter of resignation to House Speaker John Boehner, who also fought back tears. House Minority Leader Nancy Pelosi called Giffords the "brightest star among us." "She has brought word 'dignity' to new heights by her courage," Pelosi said. You will be missed in the House of Representatives. Her husband, Mark Kelly, a former astronaut, and mother, Gloria, watched. Giffords, 41, was severely injured by an assassin's bullet that tore through her skull last year in a shooting in Tucson, Arizona, that left six people dead, including a federal judge and a nine year-old girl. House Majority Leader Eric Cantor said Wednesday that "we are inspired, hopeful and blessed for the incredible progress that Gabby has made in her recovery." He called her "an inspiration to us and to all Americans." "We've missed you," added House Democratic Whip Steny Hoyer. We are blessed in this house to be served by extraordinarily people, of which you are a perfect example. The three-term congresswoman cast her final vote on a bill that she and U.S. Rep. Jeff Flake introduced in an effort to crack down on illegal drug smuggling across the U.S. border. The bill passed unanimously. Giffords has made few public appearances since the shooting, including for a vote she cast to raise the federal debt ceiling. She also gave an interview ABC's Diane Sawyer. Her appearance Wednesday in the House was her second in two days. She received a 90-second standing ovation before President Barack Obama's State of the Union address on Tuesday night. She has been undergoing intensive rehabilitation in Houston, Texas, according to her office. Loughner could face the death penalty if convicted on charges of murdering six people -- including the chief federal judge of Arizona, John Roll. Besides Giffords, the shooting injured a dozen others. He has been diagnosed as schizophrenic and has spent time on suicide watch while in custody. He is undergoing treatment in Springfield, Missouri. Giffords' formal resignation, and her husband's apparent decision not to fill her seat, now makes the race in Arizona's eighth district largely up for grabs. The remainder of Giffords' term is expected to be filled by the winner of a special election set by the state's Republican Governor, Jan Brewer.