Gabrielle Giffords will resign to focus on her recovery NEW: Rep. Wasserman Schultz says Giffords' recovery likely to take years, not months Giffords announces she will resign in a video on her website She was shot in the head on January 8, 2011 Six people died and 12 others were injured in the shooting rampage (CNN) -- Arizona Rep. Gabrielle Giffords announced on her website Sunday that she will resign from Congress this week to continue her recuperation from the brain injury she suffered when shot just over a year ago. A lot has happened over the past year. We cannot change that," Giffords, 41, says in a video on her website, speaking in a halting manner. "I don't remember much from that horrible day, but I will never forget the trust you placed in me to be your voice," Giffords continues. Thank you for your prayers and for giving me time to recover. I have more work to do on my recovery. So to do what is best for Arizona, I will step down this week. Giffords, a Democrat, will submit a letter of resignation during the week to House Speaker John Boehner and Arizona Gov. Jan Brewer. They will set the date for special elections to fill the remainder of her term, which expires at the end of the year. A statement from her office said Giffords will attend the State of the Union address Tuesday as one of her last acts before stepping down. She also will finish her "Congress On Your Corner" event that was interrupted by the shooting rampage of January 8, 2011, that killed six people and wounded 13 others, including Giffords, the statement said. House Democratic leader Rep. Nancy Pelosi, D-California, called Giffords a "bright star" whose "message of bipartisanship and civility is one that all in Washington and the nation should honor and emulate." "She will be missed in the House of Representatives, but her legacy in the Congress and her leadership for our nation will certainly continue," Pelosi said in a statement. In her website video, Giffords says her public service career has not ended. "I will return and we will work together for Arizona and this great country," she says. Earlier this month, Giffords joined thousands for a vigil in Tucson, Arizona, one of several emotional events over the weekend to mark one year since the shootings. Prosecutors accuse Jared Lee Loughner, 23, of carrying out the attack, which purportedly targeted Giffords during the constituent meet-and-greet event outside a supermarket. Giffords is still recovering from her injuries, and her right side remains weak. She has made few public appearances since the incident with some rare exceptions, such as casting a vote in Congress to raise the federal debt ceiling and conducting an interview with ABC's Diane Sawyer. She has been undergoing intensive rehabilitation in Houston, Texas, but returned to Tucson several times, according to her office. Pia Carusone, the congresswoman's chief of staff, said recently that Giffords had steadily increased her workload as her condition improved. "As the year wore on, we were able to plug the congresswoman in more," Carusone said. Rep. Debbie Wasserman Schultz of Florida, the Democratic National Committee chair, told CNN that Giffords -- a close friend -- came to the conclusion that going back to her job this year would reduce the time and work she could put into her recovery. Giffords' return to Tucson for the one-year anniversary of the shooting showed her "how challenging it would be. It came into focus then," Wasserman Schultz said. "Gaby doesn't do anything halfway," she said, using the shortened version of Giffords' first name familiar to all. She said the most important thing for Giffords was to continue her recovery, which is "more likely to be years, not months." Loughner potentially faces the death penalty if convicted on charges of murdering six people -- including the chief federal judge of Arizona, John Roll. Loughner has been diagnosed as schizophrenic and has spent time on suicide watch while in custody and is undergoing treatment in Springfield, Missouri. CNN's Tom Cohen and Dana Bash contributed to this report.