Donald Trump this morning refused to apologize for his comments characterizing John McCain as “not a war hero.” When Martha Raddatz asked Trump on ABC’s This Week whether Trump thought he owed John McCain an apology, he replied “No, not at all.”

“I will say what I want to say, and maybe that’s why I’m leading in the polls because people are tired of hearing politicians and pollsters telling the politicians exactly what to say,” Trump told Raddatz the day after Trump made his comments about McCain while speaking to a conference of religious conservtives in Iowa.

Confronted by a chorus of criticism from his fellow GOP candidates for president and from the Republican party, Trump is standing his ground as he has consistently since he launched his campaign.

Repeating his assertion that McCain hasn’t done enough for veterans, Trump said, “John McCain has failed,” citing delays in health care for veterans. “I believe that I will do far more for veterans than John McCain has done for many, many years, with all talk no action … Nothing gets done.”

Earlier this morning, Trump took his message about veterans to Twitter:

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

Trump’s GOP rivals for the nomination for president continued their criticism on other Sunday news shows.

Sen. Marco Rubio of Florida said Trump has insulted all prisoners of war, not just McCain, the 2008 GOP nominee defeated by Barack Obama. “He’s saying that somehow if you’re captured in battle you’re less worthy of honors,” Rubio said on CNN’s State of the Union. “It’s not just absurd, it’s offensive. It’s ridiculous. And I do think it’s a disqualifier as commander in chief.”

Rick Perry, a veteran, said Trump has neither the character nor the temperament for the White House. “Over the top,” the former Texas governor said of Trump on NBC’s Meet the Press. “Really offensive.”

Trump’s comments about McCain followed the Arizona senator’s saying the business mogul had “fired up the crazies” with the latter’s harsh words about Mexico and undocumented immigrants.

For that, Trump says, McCain is the one who should apologize: