It is about as subtle as a playground taunt: a television ad for Gov. Jon S. Corzine shows his challenger, Christopher J. Christie, stepping out of an S.U.V. in extreme slow motion, his extra girth moving, just as slowly, in several different directions at once.

In case viewers missed the point, a narrator snidely intones that Mr. Christie “threw his weight around” to avoid getting traffic tickets.

In the ugly New Jersey contest for governor, Mr. Corzine and Mr. Christie have traded all sorts of shots, over mothers and mammograms, loans and lying. But now, Mr. Corzine’s campaign is calling attention to his rival’s corpulence in increasingly overt ways…

Mr. Christie calls the ad “silly” and “stupid,” but there are signs that the images may be contributing to a more negative view of Mr. Christie.

In a recent survey conducted by Monmouth University, voters were asked to say the first thing that came to mind about Mr. Christie. “Fat” was one of the most frequent responses, said Patrick Murray, the director of the poll, who attributed the results to the Corzine ads.