Once again, Donald Trump isn't backing down from comments that have inflamed the Republican presidential race.

At an Iowa GOP forum Saturday, Trump dismissed Arizona Sen. John McCain's reputation as a war hero, saying McCain was merely captured in Vietnam and "I like people who weren't captured."

That's caused an uproar. But Trump isn't repentant. On Sunday, he kept up his criticism of McCain and said the senator should apologize for comments about people who attended a Trump rally focused on immigration.

On ABC's "This Week," Trump insists: "I will say what I want to say." He said the senator should apologize for comments about people who attended a Trump rally focused on immigration.



Trump also explained his own deferments during the war – four for being a student, followed by one for medical reasons. Trump said the medical deferment was for a bone spur in his foot.



He also noted his high draft number – 356 – during the 1969 draft lottery, which made him unlikely to have been called into service.



"If I would have gotten a low number I would have been drafted and I would have proudly served," Trump said.



When Trump was asked about McCain at Saturday's Iowa Family Leadership Summit, he responded, "He’s not a war hero. He’s a war hero because he was captured? I like people who weren’t captured. ... Perhaps he is a war hero, but right now, he said some very bad things about a lot of people."



"This Week" guest host Martha Raddatz pointed out the plane McCain was piloting was shot down over North Vietnam in 1967, and he was severely injured and held as a prisoner of war for five-and-a-half years in the infamous "Hanoi Hilton."



McCain, now an Arizona senator, called the people who showed up in that state to hear Trump talk about illegal immigration recently as "crazies," sparking Trump's response, but he told Raddatz he had no intention of apologizing.



Trump also attempted to turn the focus on those who have fought who weren't captured by the enemy.



"People who fought hard and weren't captured and went through a lot, they get no credit," Trump said. "They're like forgotten."



Asked by Raddatz if he has ever said anything he regretted, Trump replied, "Yes, I have, on many occasions."



Raddatz then plied Trump on what some of those things might be, including questing President Barack Obama's place of birth or on referring to most Mexican immigrants as criminals during his presidential announcement speech in June.



"No, I wouldn't do that," Trump said.



Republican commentators said the latest remarks could mark the beginning of the end of his presidential bid.

Democratic presidential candidate Hillary Clinton said Trump's comments were "shameful".

"And so is the fact that it took so long for his fellow Republican candidates to start standing up to him," Clinton added on Saturday, according to Politico.

Two fellow Republican presidential candidates, Texas Governor Rick Perry and Florida Senator Marco Rubio, speaking on different Sunday talk shows, said Trump's remarks made him unfit to serve as commander in chief.

"This is not just an insult to John McCain, who clearly is a war hero and a great man," Rubio told CNN's "State of the Union." "It's not just absurd. It's offensive. It's ridiculous. And I do think it is a disqualifier as commander in chief."

Perry told NBC's "Meet the Press" that the Republican party needed to reach out to diverse populations, not drive them away, citing Trump's recent, widely-criticized comments about Mexican immigrants.

Trump rejected calls by fellow Republicans that he drop out of the presidential race and said they were simply upset about his lead in recent polls in North Carolina, Nevada and other states.

He predicted he would win the Hispanic vote if he won the Republican presidential nomination.



Trump campaign manager Corey Lewandowski indicated the candidate would not be changing tack.

"Donald Trump is in first place in the national polls," Lewandowski told Reuters Sunday in a telephone interview from Windham, New Hampshire. "I think our strategy has worked out so far."

Trump also took to Twitter Sunday morning to further respond on the issue:

The Veterans Administration is in shambles and our veterans are suffering greatly. John McCain has done nothing to help them but talk. — Donald J. Trump (@realDonaldTrump) July 19, 2015

John McCain called thousands of people "crazies" when they came to seek help on illegal immigration last week in Phoenix. He owes apology! — Donald J. Trump (@realDonaldTrump) July 19, 2015

Trump shook up the race weeks ago when he branded immigrants from Mexico as rapists and drug dealers.