Gabrielle Giffords is to step down from the US Congress this week to concentrate on recovering from wounds suffered in an assassination attempt a little more than a year ago that shocked America.
“I don’t remember much from that horrible day, but I will never forget the trust you placed in me to be your voice,” the Arizona Democrat said on a video posted on her Facebook page.
“I’m getting better. Every day my spirit is high. I have more work to do on my recovery. So to do what’s best for Arizona, I will step down this week.”
Ms Giffords, 41, was shot in the head last January as she was meeting constituents outside a supermarket in Tucson. The shooting left six people dead, including a judge and one of Ms Giffords’ aides. Thirteen others were wounded, including Ms Giffords.
Her progress had seemed remarkable, to the point that she was able to walk dramatically into the House of Representatives chamber in August to cast a vote.
Party chiefs had hoped she might recover sufficiently to run for re-election or even become a candidate to replace retiring Republican senator Jon Kyl.
The shooting prompted an agonising national debate about supercharged rhetoric in political campaigns, although the man charged over the attack later turned out to be mentally ill.
In Washington, members of Congress were told to pay more attention to their physical security. Legislation was introduced to ban high-capacity ammunition clips, although it never advanced.
Under state law, Arizona governor Jan Brewer must call a special election to fill out the remainder of Ms Giffords’ term, which ends at the end of this year.
President Barack Obama called Ms Giffords “the very best of what public service should be”.
“Gabby’s cheerful presence will be missed in Washington,” he said. “But she will remain an inspiration to all whose lives she touched – myself included. And I’m confident that we haven’t seen the last of this extraordinary American.”
House speaker John Boehner said he saluted Ms Giffords “for her service and for the courage and perseverance she has shown in the face of tragedy”.
House Democratic leader Nancy Pelosi said that “since the tragic events one year ago, Gabby has been an inspiring symbol of determination and courage to millions of Americans”.
Jared Loughner, 23, has pleaded not guilty to 49 charges over the shooting. He has been diagnosed with bipolar disorder and is being forcibly medicated at a Missouri prison in an attempt by authorities to make him mentally ready for trial.
Ms Giffords was shot in the left side of the brain, the part that controls speech and communication.
In the months since she was shot, Ms Giffords has been treated in Houston, Texas, as well as Arizona as she re-learned how to walk and speak.
She made a dramatic appearance on the House floor on August 2, when she unexpectedly walked in to vote for an increase in the debt limit. Lawmakers from both parties cheered her presence, and she was enveloped in hugs.
More recently, she participated in an observance of the anniversary of the shooting in Arizona.
In Gabby: A Story Of Courage And Hope, a book released last year that she wrote with her husband, astronaut Mark Kelly, she spoke of how much she wanted to get better, regain what she lost and return to Congress.
She delivers the last chapter in her own voice, saying in a single page of short sentences and phrases that everything she does reminds her of that horrible day and that she was grateful to survive.
“I will get stronger. I will return,” she wrote.
Ms Giffords later vowed to finish the Tuscon meet-and-greet political event that erupted in the deadly shooting spree.
Her office said that her final act as congresswoman in her district would be to meet some of the people who were at the Congress On Your Corner event in a Safeway car park.
Those attending the private gathering will include some of the wounded, others who helped them, and people who subdued the attacker.
Ms Giffords will also visit a family assistance centre that was set up after she was wounded.