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Donald Trump on Friday launched his first attacks against Ted Cruz

Trump questioned Cruz's appeal to evangelical voters and his commitment to ethanol subsidies

Watch Jake Tapper’s full interview with Donald Trump on CNN’s “State of the Union” Sunday at 9 a.m. ET.

Washington CNN  — 

The détente is over.

Donald Trump on Friday launched his first attacks against Ted Cruz, questioning his appeal to evangelical voters and his commitment to ethanol subsidies in the first blasts by the GOP front-runner against his political ally.

Yet Trump, who has relished in whacking his Republican rivals, at times did not appear totally willing to give the same treatment to Cruz, who has yet to publicly call out Trump. Compared to some of Trump’s typical barrages against his opponents, which often include long-winded and humorous asides, his comments about Cruz on Friday were restrained and concrete.

For five months, Cruz has refused to criticize Trump even as the rest of the Republican field turned on him for a series of incendiary comments. And Trump, in turn, has spared Cruz from the missiles he’s aimed at nearly every other rival.

RELATED: Leaked Ted Cruz audio has Donald Trump readying attack

But as Cruz surges in Iowa, where Trump has long held top billing, and Cruz began to wonder aloud whether Trump could lead the country in a time of terrorism, Trump ended the peace.

“I do like Ted Cruz, but not a lot of evangelicals come out of Cuba,” he told the crowd at a town hall event at the Iowa State Fairgrounds in Des Moines. “Not a lot come out.”

The father of the Texas senator, who has appealed to the born-again believers in the Hawkeye State, escaped from Cuba as a young adult. Both of Cruz’s parents come from traditionally Catholic backgrounds, but Cruz grew up Southern Baptist.

Trump’s personal attack mirrors a previous joust at one-time top Iowa rival Ben Carson, who is a Seventh Day Adventist. Trump, who identifies as Presbyterian, implied that he was a more mainstream Christian.

The Cruz campaign declined to comment on Trump’s remarks. On Saturday, however, a Cruz-aligned super PAC, Keep the Promise, hit Trump.

“We knew when Trump criticized Cruz it would not be substantive, but we hoped it would be coherent,” the super PAC told CNN.

READ: Why Ted Cruz won’t slam Trump

The New Yorker spent more time on Friday poking Cruz for opposing ethanol subsidies, which are widely popular there. Independent groups there are beginning to spend money against Cruz for his position, which Trump told a questioner was “anti-Iowa.” Cruz says the subsidies are an example of government interference in the free market.

“With the ethanol, really, he’s got to come a long way, ‘cause right now he’s for the oil,” Trump said at the beginning of his remarks, unprompted. But then he gave him an out: “But I understand it, oil pays him a lot of money. He’s got to be for oil, right?”

“But I’m with you,” he added. “I’m self-funding. I have no oil company. I have no special interest.”

Much of the money behind Cruz’s well-funded super PACs does, indeed, come from oil wealth.

Trump later called on a pro-ethanol activist with the group America’s Renewable Future, who was given front-row seating Friday. The activist, who a group spokeswoman said was invited to the rally by the Trump campaign earlier this week, asked if Cruz’s opposition to ethanol was because of his ties to “big oil.”

“Yes it is,” Trump replied.

READ: How Cruz, Trump are trying to dominate Iowa

Both Trump and Cruz are appealing to the same disaffected GOP voters, and Trump has long said he would only hit Cruz if the Texas senator did so first. That appeared to come earlier this week, when The New York Times obtained audio of Cruz at a private fundraiser suggesting that Trump and Carson could not lead the nation given rising national security concerns.

In a tweet earlier on Friday, Trump challenged Cruz to unveil those concerns publicly, but Cruz has not yet done so.

The pair tends to lavish praise on one another, with Cruz recently saying that he could imagine Trump in his administration. Trump reciprocated on Friday evening.

“We would certainly have things in mind for Ted,” Trump told a questioner.

But for the next 50 days, Cruz and Trump appear to be barreling toward a tough fight for first place in the Hawkeye State. Trump has led most polls there, but one poll from Monmouth University this week showed Cruz with a small lead.

“What the hell is Monmouth?” Trump asked. He later conceded: “It seems like a two-person race right now.”

CNN’s Tom LoBianco, Jeff Zeleny and Sunlen Serfaty contributed to this report.