IOWA CITY, Iowa -- As soon as Republican front-runner Donald Trump took the stage at his Tuesday night rally at the University of Iowa, he demanded that members of the football team join him.

"Where's my football team? Get over here, football team," said Trump, who met privately with the student athletes before the rally. "The football team, come on! University of Iowa. Look at the size of these guys! They're monsters. We've got the next Tom Brady, right over here... Look at the size of these guys! Come on up here. Come on up, right? Get up! What a team, what a team. And they were so nice: They endorsed Trump. They like Trump, and I like them. I love you guys. Look at the size, how big and strong. That's what we like. Thank you, fellas."

A dozen football players, nearly all dressed in suits, filed onto the stage and lined up behind Trump. He shook their hands, and they filed back off the stage. The crowd started chanting, with Trump conducting them: "Let's go Hawks! Let's go Hawks!"

This liberal college town isn't the sort of place one might expect Trump to attract a rowdy, mostly supportive crowd. Yet roughly 2,000 people packed into part of a university gymnasium on Tuesday night and loudly cheered as Trump called for building a massive wall along the southern border, putting Democratic front-runner Hillary Clinton in jail, killing Common Core and replacing the Affordable Care Act.

[Here's how the Iowa caucuses work]

The crowd was a mix: Republican couples who live in and near the college town, young professionals who recently graduated and large packs of teenaged and 20-something guys who acted as if they were at a high-stakes basketball game. Nearly everyone marveled at out-numbering the liberals for once.

"They're all here, they just come out of the woodwork when it's their time," said Michael Chizek, 19, a freshman business major from Clear Lake, Iowa, who came to the rally with his buddies Nate, Blair, Mitch and Austin. "Donald does that, he gets people going -- he shows them what's wrong with their country, and they get angry. Something's wrong if you're not angry about the direction our country's taking."

After recognizing the football team, Trump shifted to wrestling -- a sport the candidate once engaged in as a much younger man. Trump said he likely could not take out any of the guys on the team, even the one who is injured and currently using crutches.

[With the caucuses approaching, Trump and Cruz target evangelicals]

"Get the wrestlers up here," Trump said. "Come on, fellas. Where are they? Where are they? These guys -- I'm not messing with 'em... Look at these guys. Undefeated team, University of Iowa."

The seven wrestlers were dressed far less formally than the football players. One wore a hat with a tiny propeller on top, while another sported an American flag jacket. The crowd did not break into a chant for them.

Trump said running for president is difficult and "takes guts," just like being a student athlete.

"This is tough stuff -- I mean, coming around and doing this," Trump said. "As much as I love you people, I could be someplace else."

Trump then gave his review of the Democratic debate the night before: So boring that he couldn't watch it, even though he tried three different times. He described those on the stage: "A communist," which must have been a reference to Sen. Bernie Sanders (I-Vt.) and Clinton, "who is a disaster." Before Trump could get to his usual attacks on former Maryland governor Martin O'Malley (D) -- which usually involves not remembering who he is -- a group of protesters erupted.

[Donald Trump's closing pitch in Iowa: "I get along with people."]

It was, after all, Iowa City. Before the rally even started, there were several commotions in the crowd -- a heated argument broken up by security, a burst of anti-Trump signs and a guy who repeatedly bellowed, "Fascists out of Iowa!" before showing himself out. Trump's 35-minute speech was repeatedly interrupted, often by protesters blowing whistles.

At the first outburst, Trump smiled. He loves to hate protesters.

"You wanna let the football team take care of it?" Trump said with a smirk, as the crowd cheered. "It is incredible,  isn't it, though? It's incredible, I'll tell you. It's so incredible."

Trump said the only time television cameras leave his face and show his crowd is when a protest breaks out.

"Anybody wanna protest?" Trump said. "Go ahead, it's fine."

Trump rattled off some poll numbers, called one of his rivals a "nervous wreck" and reminded Iowans of just how important it will be to caucus on Feb. 1.

"Iowa -- like your football team, like your wrestling team -- Iowa needs a win," Trump said. "Sixteen years, you haven't picked a winner. For 16 years, you haven't picked a winner. Now, you're going to pick a winner. It's going to be Trump."

[Meet the towns that love Donald Trump]

Then it was back to poll numbers -- interrupted by a whistle.

"Who the hell is that? A protester?" Trump said. "Sounds like a protester."

Supporters in the crowd began chanting Trump's name, and he joined in: "Trump! Trump! Trump!"

"Don't worry," Trump said. "That's a nice whistle. Actually, I think they're wrestling in the back of the room."

Minutes later: more whistles. This time, Trump seemed annoyed and repeatedly yelled: "Get the hell out of here!" Trump said that he could convert any protester to his way of thinking in just 10 to 15 minutes, unless they have a "substance abuse problem."

"What are they doing?" Trump said. "It's really protest just for the sake of protesting, really."

Several minutes later, more protesters.

"These people," Trump said, "these people."

He then quietly waited, drumming his fingers on the sides of his lectern as the crowd took over the policing. "Get them out of here," various voices shouted. "Get them out."

"Bye, bye, darling," Trump said, growing exasperated as another protester was led out. "It's like one person here, one person there."

A guy in the crowd shouted: "We love you Donald." He replied: "I love you, too, man. I love you. I love you, too. I love this country." The crowd cheered.

Trump returned to discussing the importance of the Iowa caucuses and ethanol, which he said is "a very important thing to the farmers." Then onto the Iraq war. And then, another whistle.

[76 things Donald Trump promises to do as president]

"Oh no, not again," Trump said shaking his head. "Oh, throw 'em the hell out of here. Am I allowed to rip that whistle out of the mouth? I'd rip that whistle..."

Trump screwed up his face. He rearranged his notes.

"I'd rip it right out," he said. "I would rip that whistle -- should somebody do that?"

"Yeah!" several people in the crowd shouted. The whistle continued.

Trump put his notes into his blazer pocket. He gripped the lectern.

"Oh boy, oh boy, oh boy," Trump said. "Okay, maybe we should bring that person up, have a little debate with that person? Isn't it terrible, though? Isn't it terrible? I mean, where do these people come from? You really wonder."

The whistle continued and continued. Several people in the crowd shouted: "Shut up!"

Trump wrapped things up. Barely 35 minutes had passed, making this speech about half the length of his usual remarks.

"Iowa is so important. So, are you ready?" Trump said. "We are going to win so much. We're not going to lose any more."

Trump left the stage and took his time on the rope line, signing copies of his books, campaign signs and red ball caps. He posed for numerous photos.

"It was awesome," said Nate Katalinich, 18, a senior at the local high school who plans to caucus for the first time for Trump. "It's way different from seeing it online. It's like electric being here. It's a lot more energy."

Tyler Rowe, 20, and a bunch of his friends from the dorm waited along the barricade in hopes of meeting Trump.

"It was rowdy," said Rowe, a sophomore pre-med and history major from Altoona who was seeing Trump for a third time. "This time it was different. The energy was crazy."

Just then Iowa starting quarterback C.J. Beathard came up to the barricade.

"There's C.J." one of the guys said. Another asked: "C.J. Can I get a picture real quick?"

"Wait, wait, wait," Rowe said, going in for his own selfie with the famous student athlete. "Mr. Beathard, Mr. Beathard, I want one."

[Here's how Beathard became a target for selfies]

Nicholas Fraizer, a 19-year-old freshman business major from New Orleans, said he was impressed Trump got the university's most well-known students on the stage.

"That was pretty cool," Fraizer said, as his friends took photos with Beathard. "That was really smart on his part, playing on the wrestling, the basketball and the football success. I mean, that's like a quick way for us Iowans -- we love our football, wrestling and basketball."