Donald Trump on Sunday declined to apologize for his comments about war veteran and Arizona GOP Sen. John McCain, suggesting the backlash is being fueled by fellow Republican presidential candidates trailing him in the polls.

“Republican candidates, some of whom are registering one percent and zero, they're very upset that I'm leading the polls by actually a nice margin,” Trump, a self-funded, billionaire real estate mogul, told ABC’s “This Week.” “They started attacking me.”

On Saturday, Trump acknowledged that McCain, a former Navy fighter pilot who spent five-and-a-half years as a prisoner during the Vietnam War, was indeed a war hero but only “because he was captured.”

“I like people who weren’t captured,” he also said.

The feud between Trump and McCain appeared to have started during a recent event in Phoenix, Ariz., that swelled to 1,500 people, many apparently energized by Trump suggesting that he would, if elected, build a wall along the southern U.S. border and that some Mexicans coming into the country are rapists and drug dealers.

McCain, whom Trump financially backed in his failed 2008 presidential bid, called the attendees “crazies,” which upset Trump, who called for an apology.

Most of the 14 other GOP candidates have condemned Trump’s remarks about McCain, including Florida Sen. Marco Rubio and former Texas Gov. Rick Perry who are calling for Trump to quit the race.

“This is not just an insult to John McCain, who clearly is a war hero and a great man,” Rubio said on CNN’s “State of the Union.” “But it's an insult to all POWs, to all men and women who have served us in uniform, who have been captured in battle. … It's ridiculous. And I do think it is a disqualifier as commander in chief.”

Within hours of Trump’s “war hero” comments, Perry called for him to drop out, and he repeated his position Sunday.

“I really don't understand his strategy here of taking on a bullet that went through John McCain and a hit a lot of us that wore the uniform of this country,” Perry said on NBC’s “Meet the Press.” “And I still stand by my statement. Until Mr. Trump apologizes directly to John McCain and to the veterans of this country, I don't think he has the character or the temperament to hold the highest position in this country.”

McCain has yet to respond.

“I'm certainly not pulling out,” Trump told ABC. “I'm leading and I'm leading in many states. … And I will win the Hispanic vote.”

Trump also said he received a standing ovation after the event Saturday in Ames, Iowa, at which he made the comments and that “nobody was offended.”

“This whole thing was brought up by a lot of the people that are competing against me currently that aren't even registering in the polls,” he said.

Trump also repeated earlier criticism about McCain failing to use his elected position of power to improve the trouble Department of Veterans Affairs so that veterans could get better health care without the exceedingly long waits.

“It's a scandal. And John McCain has done nothing,” he said, before waving off criticism from veterans’ groups, saying, “Maybe they don't speak to the same vets that I speak to.”