Trump has celebrated eminent domain not just for public use, but for private use as well.
And on the debate stage on Saturday, Bush pounced on the billionaire businessman, using the same incident as seen in the ad involving a parking lot at a casino to paint Trump as an overzealous land-grabber.
"What Donald Trump did was use eminent domain to try to take the property of an elderly woman on the strip in Atlantic City," Bush said. "That is not public purpose. That is down right wrong."
"Jeb wants to be a tough guy tonight. I didn't take the property," Trump shot back, saying he walked away from the deal.
Trump, as a real estate magnate, has defended the government power, protected in the Constitution, as needed for public projects like roads and highways.
Conservatives wary of the overgrown state -- like those in New Hampshire -- are sharply critical of the power to seize property for private projects, like casinos, that was made possible thanks to a 2005 Supreme Court decision, Kelo v. New London.
"A lot of the big conservatives that tell me how conservative they are, I think I'm more conservative than they are," Trump said.
Trump repeatedly pointed to the Keystone XL pipeline as an example of something that conservatives support, but which wouldn't be possible without eminent domain.
"The Keystone pipeline -- without eminent domain, you wouldn't go 10 feet, okay?" Trump said.
Cruz's campaign has seen that as a key vulnerability for Trump here in New Hampshire, and his campaign's first attack ad on Trump centered on that very issue.