David Jackson and Penelope Overton

USA TODAY

Presidential candidate Marco Rubio Saturday warned fellow Republicans against the party being defined by Donald Trump, and suggested he may have to disavow the GOP frontrunner if Trump becomes the nominee.

"I still at this moment intend to support the Republican nominee," Rubio said. "But … it's getting harder every day.”

Later, during a rally at an industrial park in Largo, Rubio told supporters of Trump:

"If he is our nominee, this is what our party is going to be defined by."

Citing Trump's comments that he would like to punch a protester in the face, or that he would pay the legal fees of supporters who do so, Rubio said Trump's rhetoric is feeding into people's anger and encouraging behavior that leads to violence.

Rubio supporters said professional protesters appeared to start the problems at the Trump rally, but the billionaire's rhetoric has created a toxic atmosphere.

"It's kinda nice he says what he thinks," said April Powers, 54, an accountant from Pinellas Park, Fla. "But sometimes he's just way over the top -- he's too much."

Janet Rontos, 79, a retired school teacher from Largo, said Trump encourages rough stuff with his rhetoric.

"'Punch 'em in the face! Get 'em out of here!'" she said, imitating Trump.

Rontos added, however, that "he'll get away with it" because Trump's supporters are so fervent.

After a strong showing in Thursday's Republican debate in Miami, Rubio is positioning himself as the anti-Trump vote in the Florida primary. Rubio had this message for the Florida supporters of Texas Sen. Ted Cruz and Ohio Gov. John Kasich.

Donald Trump cancels Chicago rally after protesters, supporters clash

"I don't blame people in Ohio if they conclude that, while they like me, the only way to stop Trump there is to vote for Kasich," Rubio said in Naples Friday. "I have made the argument here in Florida that If you're a Ted Cruz supporter or a John Kasich supporter, voting for them in Florida means you're voting for Donald Trump because I am the only one who can beat him in Florida."

He talked directly about the high stakes of Florida's outcome. "I've always felt that the winner of the Florida primary is probably going to be the nominee," he said.

But he stopped short of saying he would drop out if he lost the primary in his home state. "We haven't even thought about that," he said. "We're just focused on winning Florida."

In the chaos of a heated campaign, however, Rubio admited that he regrets the tone of his political attacks on Trump, although he said they were in response to Trump's own negativity.

Rubio spent about 15 minutes greeting people eating late lunches at the Yabba Island Grill and a crowd of about 200 supporters who crowded into Sugden Plaza with Rubio bumper stickers, signs and copies of Rubio's book 100 Innovative Ideas for Florida in downtown Naples on Friday afternoon. The crowd was made up largely of snowbirds, some from as far away as Iowa and Massachusetts, although a few locals ducked out from work to see their home state political celebrity.

"Marco gave me a hug," squealed Lindy Connor, a Massachusetts resident who is wintering in Sarasota. "I told him I was from Massachusetts and I voted for him and he said wow and then I guess that he just had to give me a hug. I told him he has people who love him, even up in liberal land."

Not every one in the crowd was a supporter, however. John Moore of Naples came out with a handmade sign held high urging Rubio to drop out of the race to give Cruz Florida's 99 delegates.

"I voted to send Rubio to the Senate," Moore said. "He was the Tea Party's guy then and I gave him my vote. But now, he needs to reinforce his dedication to the cause and prove to me that he is really a patriot and step down in time to give Cruz our delegates.

“That is what a true conservative would do. He wouldn't let his ambition hurt the cause. He wouldn't let his political ambition serve up Florida, and most likely the United States, on a silver platter to Donald Trump."