"I'm happy to say that she's holding her own," he said.
Giffords, a three-time Democrat, remained in critical condition at Tucson's University Medical Center since Saturday when she was shot during a meeting with constituents outside a grocery store. The attack killed six and injured 14 others. Six remained hospitalized.
Giffords previously raised two fingers with her left hand and gave a thumbs-up when responding to doctors' verbal commands.
Although her condition has remained virtually unchanged the past few days, doctors were hopeful.
"She has a 101 percent chance of surviving," said trauma chief Dr. Peter Rhee said. "She will not die. She does not have that permission from me."
Doctors initially thought the bullet entered the back of the skull and exited the front, but after reviewing X-rays and brain scans, two outside physicians brought in by Giffords' medical team now believe that Giffords was likely shot in the front of her head.
Giffords was lucky the bullet did not cross into both sides, or hemispheres, of the brain, which can leave lasting damage, her doctors have said.
As doctors continued to monitor Giffords' recovery, details emerged about the care she received when she was rushed by ambulance to the hospital.
Trauma surgeon Dr. Randall Friese was the first to treat Giffords.
"I immediately went over to her bedside and began to coordinate her care," he said.
That meant going through a checklist much like what a pilot would do before taking off. Doctors checked to make sure there weren't any other bullet wounds, put in a breathing tube and assessed her mental state.
Despite not knowing if Giffords could hear him, Friese said he took her hand and told her that she was in the hospital and that doctors would take care of her.
"Then I said, 'Squeeze my hand, Mrs. Giffords.' And she did," recalled Friese.
He asked her several more times to press his hand and she responded.
