GABRILLE Giffords, the Arizona congresswoman who survived an attempted assassination last year, is to resign on Monday to concentrate on her rehabilitation, she announced on Sunday.
In a video message to supporters, released just over a year after she was shot through the head, Ms Giffords, 41, said: "I have more work to do on my recovery. So to do what is best for Arizona, I will step down this week".
Speaking haltingly, she tried to reassure residents of Tucson, where Jared Loughner killed six people and injured 13 at a meet-the-voters event outside a supermarket last January, that her condition was continuing to improve.
"I am getting better every day," she said in the two-minute clip. "My spirit is high. I will return and we will work together for Arizona and this great country.
"I don't remember much from that horrible day, but I will never forget the trust you placed in me to be your voice. Thank you for your prayers and for giving me time to recover."
Ms Giffords, who was initially reported to have been killed, surprised doctors with her remarkable recovery. However, by passing through her brain, Loughner's bullet damaged her ability to articulate complex sentences and limited the use of the right side of her body.
She has spent the past year receiving treatment at a specialist centre in Texas. Ms Giffords is expected to submit a letter of resignation to John Boehner, the House Speaker, today. A by-election will then be held to fill her seat.
Ms Giffords was first elected to the US House of Representatives in November 2006. Before quitting she is expected to finish the "Congress On Your Corner" event that was disrupted by Loughner's rampage.
It has been speculated that Mark Kelly, Ms Giffords's husband and a recently retired astronaut, may run to take the seat. He said in July that a career in politics was "not the plan right now" but added: "I've learned over a lot of years that you should never rule anything out."