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Donald Trump goes after Ted Cruz at Iowa rally

One friendly re-tweet didn't mean Trump isn't ready and willing to go after Sen. Ted Cruz.

DES MOINES, Iowa — One friendly re-tweet didn't mean Donald Trump wasn't ready and willing to go after Sen. Ted Cruz.

The two Republicans were rivals largely in name only until Friday night, when Trump questioned Cruz's stance on renewable fuel as well as his faith.

Asked by one attendee if Cruz doesn't support the renewable fuel standard because of his "ties to big oil," Trump responded, "yes."

"He's from Texas. Lot of oil in Texas," Trump said.

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Then Trump posed a question that could be poisonous to Cruz's rise in the ethanol-friendly state: "If Ted Cruz is against ethanol, then how does he win in Iowa?"

Trump made the comments after he warned Cruz would "fall like the others" if he decided to attack the billionaire. Trump was responding to a New York Times report that said Cruz questioned Trump's judgment in a closed-door meeting. Cruz called the report "misleading."

Cruz does support eliminating the renewable fuel standard, but that's not the only energy subsidy he supports ending.

Rick Tyler, a Cruz spokesman, told NBC News just last week that Cruz "is for eliminating all energy-specific subsidies," not just the RFS but oil and other sources as well.

It's an issue that hits close to home for Iowans because it requires a certain amount of ethanol and other biofuels to be used in the U.S. fuel supply. The standard expires in 2022 but Cruz has advocated for its expiration before then.

Trump couched all of his Cruz criticisms in admiration Friday — embracing the man who just hours before the rally tweeted that Trump was "terrific."

Trump acknowledged that he even re-tweeted this sentiment, and that Cruz's kind words are rarity in a field that's been quick to condemn Trump, especially in light of his recent proposal temporarily bar Muslims from entering the U.S.

"I like Ted Cruz a lot," Trump said, responding to another question from Eagle Forum, this one about if he would appoint Cruz to the Supreme Court or tap him to be his vice president.

"He's doing well, I'm doing well," Trump said before drawing an important distinction to the few-thousand-person crowd: "There's not a contest between the two of us."

Trump then said that he'd "certainly have things in mind for Ted."

Trump told the crowd he was "doing really well" among Evangelicals — a group that Cruz is also courting, and which has shown him support so far.

"I do like Ted Cruz," Trump once again hedged. "But not a lot of evangelicals come out of Cuba, in all fairness."

When Trump wasn't talking about Cruz, he was talking about polls — and why they spell a win for him, not just in Iowa but across the country. Trump made a a big prediction: if he wins it in Iowa, "we're gonna win everything after that."

And while Trump admitted, "I only like polls that treat me well," that doesn't change the reality that most polls do show him ahead of the field, with large leads over his rivals.

The Real Clear Politics polling average shows Trump at 30.4 — his nearest competitor, Ted Cruz, coming in at about half that number, 15.6.

Noticeably absent from Trump's Friday remarks: Promises to temporarily ban Muslims from the United States, although he was asked at one point about Syrian refugees coming into the country by way of the Southern border.

Trump responded that he'd "build a wall" and even guessed that someday they would name it the Trump Wall.

Standing on a stage without a podium, a first for a man who often speaks from behind a lectern, the event felt like a true town hall as opposed to Trump's usual raucous rally. He noted at one point that "it's big but it feels intimate."

Trump took questions for nearly an hour, many from special interest groups like Veterans for Strong America, which endorsed Trump earlier this summer.

For those in the crowd, many just wanted to hear Trump's thoughts in person.

"I think a lot of his stuff gets twisted around," Kim Norby, 49, told NBC News. "I wanted to hear all the context." He's not 100 percent, but said he'd be interested in caucusing, possibly for Trump.

"I'm mostly supporting him," Norby said.

Brandy Dacken attended the rally unsure if she'd support Trump, but open to his signature matter-of-fact style and lack of concern for political correctness.

"I like the things that Trump has to say. Sometimes they're kind of harsh but I guess that's why I'm here — to just see what he has to say tonight, form my own opinion," she said. National security and foreign threats were among her top concerns.

Pat Solberg has caucused previously — but for Democrats. This time, she's planning on coming out for Trump.

"I think he's the only one who can make things great again," Solberg said. "He hasn't been bought and paid for."

This article first appeared on NBCNews.com.