SIOUX CITY, Iowa -- Newt Gingrich chided his GOP presidential opponents in a new TV ad for going negative but conceded later Thursday that the attacks could well take a toll on his support in the run-up to the Iowa caucuses on Jan. 3.
"I would be very surprised if we didn't see some ups and downs over the next three weeks," the front-running former House speaker told Iowa Public Television.
Gingrich commented hours before he and six rivals were to meet in Sioux City for their final pre-caucus debate, with Gingrich intently focused on staying ahead of the pack and the others trying anew to derail him.
The debate will be a crucial moment for him to show poise in the face of the attacks, Republican Iowa Gov. Terry Branstad told The Associated Press.
Branstad said he was unlikely to endorse a candidate and was unsure whether Gingrich has what it takes to be president.
"I think he's a great idea person. I have a lot of respect for him," Branstad said. "But whether he has the discipline and the focus, I don't know."
Chief rival Mitt Romney and his allies are waging an aggressive effort to discredit Gingrich in the eyes of conservatives at campaign events, media interviews and through independent advertising. Ron Paul also is going after Gingrich on television, and Michele Bachmann, Rick Perry, Rick Santorum and Jon Huntsman have sharpened their criticism.
Campaigning later in Sioux City, Gingrich responded to Branstad's comment by suggesting Branstad "watch and decide," and said he had "no idea" why the questions persist about his discipline.
He ticked through a list of accomplishments he suggested required discipline, such as leading the 1994 Republican takeover in the U.S. House, passing four consecutive balanced budgets, and helping enact welfare reform with Democratic President Bill Clinton in the 1990s.
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