James Eric Fuller, 63, was detained on misdemeanor disorderly conduct and threat charges Saturday during the event taped for a special edition of ABC's "This Week," Pima County sheriff's spokesman Jason Ogan said.
He apparently became upset when Trent Humphries suggested that conversations about gun control be delayed until all the dead were buried, KGUN-TV in Tucson reported.
Authorities said he took a picture of the leader and yelled "you're dead."
Ogan said deputies decided he needed a mental health evaluation and he was taken to a hospital, which will determine when he will be released.
Fuller, who said he was hit in the knee and back, was one of 19 people shot at a Safeway store Jan. 8. Six people died and Rep. Gabrielle Giffords remains in critical condition with a bullet wound to the head.
Giffords was continuing to progress Saturday, with doctors replacing the breathing tube that connected her to a ventilator with a tracheotomy tube in her windpipe. They could soon know if she can speak, but they didn't offer a timeframe. Doctors also installed a feeding tube.
In its story on the arrest, The New York Times said Fuller reported last week that he had trouble sleeping after he was wounded.
The paper said that in an interview last week, Fuller repeatedly denounced the "Tea Party crime syndicate," and said he placed some of the blame for the shooting on Sarah Palin and other Republican leaders, saying he believed they had contributed to a toxic atmosphere.
Meanwhile, as Tucson attempted to heal, the Safeway supermarket reopened and a memorial of flowers quickly grew outside.
Randy Larson, 57, came by to shop but instead found himself sitting quietly on the curb choking back tears.
"I wanted to come here now and see it now and not two weeks later when it's just a grocery store. I honestly kind of thought, 'Well, I'll come and patronize them and shop' but it's really hard to, because by doing that it's going about your day as usual," said Larson, who runs a sandwich shop in the same shopping center.
"I can't come here and go about my day as usual," he said. "Why should it be usual for me when it's not for the victims?"
Paramedics on the first three engine trucks to respond to the Safeway parking lot a week ago where Giffords was meeting with constituents recounted the scene that unfolded as they rushed to count and triage the victims.
Veteran paramedic Tony Compagno stepped off Engine 30 and panicked people rushed his crew, trying to pull them toward the injured, while three men desperately gave chest compressions to 9-year-old girl Christina Taylor Green, who was killed in the attack.
Others cried out "Giffords! Giffords!" and pointed to a woman lying unconscious with a gunshot wound to the head. Several other bodies were already covered with sheets.
"I started counting and my mind, it was hard to remember what I was counting because of the chaos there was. I counted, I forgot what I was counting, I went back really quick and counted again," Compagno said. "I have no idea of the time that went by, I have no idea how long it took me."
Elsewhere in town, an organization called Crossroads of the West held a gun show, one of many it hosts in several Western states. An estimated crowd of 4,000 showed up, though the mood was less upbeat than past shows, organizer Bob Templeton said. Gun enthusiasts mingled in the county fairgrounds building, discussing Second Amendment rights and buying handguns, rifles and other weapons.
The group considered canceling the event, but decided Tuesday it would go on, said Templeton, adding that the shooting was not about gun rights, but rather "a deranged person who was able to carry out whatever his agenda was."
Also Saturday, Pima Community College released a video - first to a Los Angeles Times public records request and then to The Associated Press - that shows suspected shooter Jared Loughner, 22, giving an improvised nighttime campus tour and rambling about free speech and the Constitution.
Loughner's voice provides an angry narration that includes statements such as, "I'm gonna be homeless because of this school," and calling Pima "a genocide school." College officials confirmed that the video, discovered on YouTube, led them to suspend Loughner from school Sept. 29.
Christie reported from Phoenix. Associated Press writer Alicia Chang in Tucson also contributed to this report.