That characterization, however, has been challenged. Part of the criticism hinges on the idea that she thwarted an actual vote. The Arizona Daily Star pointed out that Giffords evoked a quorum call to stop a nighttime introduction of a bill onto the full Senate floor, a move that in Arizona precedes an actual up-or-down vote on the measure. The introduction of the bill was delayed a single day, at which point it was sent to the Senate Appropriations Committee for consideration.

Then there is the ad's contention that Giffords "forced budget talks out in the open." The Appropriations Committee met to consider the budget package for days before clearing it for an actual vote on the Senate floor. The committee would have had this role even if the bill had been introduced at night.

What's worse, Giffords, a member of the Appropriations Committee, was in Washington, D.C., for a meeting of the moderate Democratic Leadership Council when the appropriations panel took up the bill, a move that's coming under fire in light of the ad.

"If Giffords had been present to vote and voted against the bills," writes the Star, "she would have created a tie, killing the bills in committee."

Giffords's campaign has defended the advertisement. An E-mail sent to supporters on Thursday--one day after the Star article ran--quoted State Sen. Bill Brotherton, assistant Democratic House leader Rep. Linda Lopez, and former Sen. Slade Mead defending the TV spot.

The campaign's argument hinges on the idea that by delaying the introduction of the bill by a day, Giffords also, as the release puts it, "delayed an eventual final vote on the bill by one... day, because Senate rules require that bills be reviewed three times on three separate calendar days."

And by the time those three days were up, one senator had gone home for vacation, and Republicans couldn't cobble together the 16 votes they needed to pass the budget. The release doesn't address questions about whether Giffords brought discussions on the budget out from behind closed doors.

"Giffords's action helped run out the clock," Brotherton said in the campaign release. "Her advertisement is accurate."