— -- Donald Trump may love calling Jeb Bush "low-energy," but Ted Cruz appeared to have some advice for the real estate mogul's campaign Friday -- "You don't do it sitting back from the easy chair."
"You don’t do it from a studio in Manhattan," Cruz told ABC's Tom Llamas. "You do it on the ground."
The comments, which came on Day Five of Cruz’s marathon six-day bus tour across Iowa, were in response to a question about whether Cruz believed Trump is working hard enough in the state.
Although Cruz never said Trump's name during the exchange, he did invoke "Trump Force One," the real estate billionaire’s private Boeing 757.
"I feel confident I’m never going to have a plane with my name painted on it," Cruz quipped. Cruz later added that "humility" was a necessity on the trail.
However, Cruz was quick to clarify that he had no intention of causing ill-will between himself and Trump.
"Our friends in the media desperately want Donald and me to engage in a cage match," Cruz said. "I am not interested in throwing rocks at Donald Trump or any other Republican running for president."
Cruz has made a point of emphasizing his "grassroots" efforts, particularly in the battleground state of Iowa, vowing to visit all 99 of its counties and often packing up to five or six stops in a day. Cruz has also largely avoided direct political combat with Trump even as the Republican frontrunner has raised questions about Cruz’s eligibility to be president.
On the trail in Mason City, Iowa today, Cruz also faced questions about his citizenship from a voter.
"I have never breathed a breath of air on this earth that I'm wasn't a U.S. Citizen," Cruz said, adding that the attacks were due to his rising popularity in the race.
In an interview with ABC News earlier this week, Cruz opened up about this toll the campaign has taken on his personal life.
"You miss a lot of moments" Cruz said, expressing remorse at being away from his daughters.
At today's stop, however, Cruz doubled down on the his commitment to campaign "on the ground."
"Every day from now until caucus day and every day from now and until this nomination is decided and every day until the general election I intend to work to continue trying to earn the support of the men and women in this country," he said.