As soon as he said it, a creative mind could imagine the negative ad. On Nov. 13, during Ben Carson's brief surge in Iowa polls, Donald Trump turned part of his Fort Dodge appearance into a live "Mythbusters" episode, reenacting Carson's stories of teenage violence, asking how anyone could believe them.

"How stupid are the people of Iowa?" Trump asked, after wondering how Carson could have narrowly avoided stabbing a friend by hitting his belt buckle. "How stupid are the people of the country to believe this c--p?"

[Donald Trump begs Iowans not to believe Ben Carson: ‘Don’t be fools, okay?’]

The clip sat in the ever-growing archive of Trump gaffes, ready for redeployment, until Tuesday morning. In "New York Values," Sen. Ted Cruz (R-Tex.) uses the clip to make a point that Trump's rivals feel should be obvious — this Manhattanite does not understand Iowans. Like "Extreme," an ad that a pro-Cruz super PAC began running Monday, it plays a 1999 clip of Trump admitting he's "very pro-choice" because his values came from New York, not Iowa.

"What does Trump think about Iowa?" asks a concerned narrator.

"How stupid are the people of Iowa?" asks Trump. The context — that they were only truly stupid if they believed Carson — is predictably cut out.

"Donald Trump: New York values, not ours," concludes the narrator.

While the ad complements Keep the Promise's abortion-themed "Extreme" spot, it overlaps jaggedly with the super PAC's other Iowa/South Carolina ad. That one features Trump, at a 2014 Florida GOP fundraiser, shoveling praise on Cruz — the man who is now revealing that Trump has odious New York values.

In his regular early morning TV interviews, Trump dismissed the new spot as a "lie" from Cruz.

"I am pro-life, and everyone understands that," Trump said. "When I said 'How stupid are the people of Iowa,' then I said, 'How stupid are the people of the United States?' And what I was talking about was everybody believing a candidate who's not doing too well. Ted Cruz is a liar. He lies."