Donald Trump says he is "a nice person" despite his ongoing quarrels with fellow Republican candidates.

The frontrunner in some polls of GOP primary voters appeared on Fox News' "Fox & Friends" Wednesday to discuss his latest quarrel with Sen. Lindsey Graham, R-S.C. The hawkish senator repeatedly called Trump a "jackass" on Tuesday, leading Trump to retaliate by sharing Graham's cellphone number with a packed crowd at a campaign event later in the day.

"I did it for fun and everybody had a good time," Trump told the show's hosts. "I don't regret it at all."

The real estate magnate appeared on the network shortly after two of his GOP rivals — Sen. Marco Rubio, R-Fla., and Carly Fiorina — were featured on the morning program to discuss their own campaigns. Both Rubio and Fiorina were asked about Trump's progress in the polls and his remarks about Sen. John McCain's, R-Ariz., valor during their separate interviews.

"I don't think the way he's behaved the last few weeks is either dignified or worthy of the office he seeks. We already have a president now that has no class," Rubio said.

Less than an hour later, Trump fired back and speculated that he's being attacked by fellow Republican candidates because of his lead among them.

"All of a sudden these guys are calling me names [and] I'm trying to be nice — I want to be nice. I'm a nice person," he said. "But everybody's calling me names and I guess — since I went to number one in the polls — they're having a field day on me."

Host Steve Doocy followed up by telling the former reality TV host that somebody had recently compared him to a Navy SEAL since "[Trump] never backs down when he's in a fight."

When asked about McCain, Trump said he respects the Arizona senator, but would do a better job as president to fix the broken Department of Veterans Affairs.

"Nobody will do for the vets, what I will do for the vets," he said. "I would take better care of the vets than anybody because I know how to do it and I know how to manage."