Story highlights Ted Cruz took several shots from the campaign trail at GOP rival Donald Trump

Trump has called Cruz's eligibility to be president into question since the Texas senator was born in Canada.

(CNN) Under assault from Donald Trump, Ted Cruz offered something of a thinly veiled contrast Friday here with his Iowa rival that he's a bit more down to earth than the billionaire businessman.

Cruz, in the middle of an intense 28-county bus tour, has been arguing that he is out working the GOP field on the ground as they rely on "slick Hollywood TV ads."

Asked by reporters if he had much faith in the ground game of a Trump, Cruz mocked his opulence.

"I feel confident that I'm never going to have a plane with my name on it," he said at a church. "How do you run a grassroots campaign? It's very time intensive. It's labor intensive. You don't do it sitting back in the easy chair. You don't do it from a TV studio in Manhattan."

Cruz has consistently poked fun at Trump's wealth, telling a late night host that he would like Trump to write his campaign a large check and joking in a GOP debate that the New York builder should personally pay for a wall on the Mexico border.

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