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Donald Trump didn't hold back Saturday when asked about his recent remarks calling Arizona senator and former presidential nominee John McCain a "dummy."

The Republican Party elder lost the White House in 2008 to then-Democratic candidate Barack Obama.

"I don't like losers," Trump, a Republican presidential contender for 2016, said at the Iowa Family Leadership Summit during a question-and-answer session.

Moderator Frank Luntz described McCain — a former naval pilot taken prisoner for almost six years during the Vietnam War — as a "war hero."

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The real estate mogul then took a swing at McCain, whom he said he had supported in 2008.

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"He's not a war hero," Trump said mockingly. "He's a war hero because he was captured. I like people that weren't captured."

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He then changed his tune, adding, "He's a war hero because he was captured. OK, I believe — perhaps he's a war hero."

Trump, who has come under fire in recent weeks for his comments on illegal immigration, is among 10 GOP candidates speaking at the Family Leader Summit, a conference of religious conservatives.

Trump first tweeted Thursday that McCain was a "dummy" after the senator criticized his July 11 rally in Phoenix against illegal immigration.

"This performance with our friend out in Phoenix is very hurtful,” McCain told The New Yorker after the event. "Because what he did was he fired up the crazies."

McCain's daughter, Meghan McCain, also a political commentator, tweeted Saturday that she was "disgusted" by Trump's words.

I can't believe what I am reading this morning. Horrified. Disgusted. There are no words. — Meghan McCain (@MeghanMcCain) July 18, 2015

Trump, whose own lack of military service has been called into question in the past, said later Saturday that he did not go to war because he was a student at first, and then because of bone spurs in his foot, reported MSNBC. He added that he opposed American military action in Vietnam at the time.

“I was not a big fan of the Vietnam War,” Trump said. “I wasn’t a protester, but the Vietnam War was a disaster for our country. What did we get out of the Vietnam War other than death? We got nothing.”

Other GOP presidential contenders, including Louisiana Gov. Bobby Jindal and South Carolina Sen. Lindsey Graham, quickly came to McCain's defense, calling Trump's comments disrespectful — and said he's not fit to represent the party.

Enough with the slanderous attacks. @SenJohnMcCain and all our veterans - particularly POWs have earned our respect and admiration. — Jeb Bush (@JebBush) July 18, 2015

.@realDonaldTrump's comments today make him unfit to be Commander-in-Chief https://t.co/EVl1X66gHo — Rick Perry (@GovernorPerry) July 18, 2015

But Trump continued his tirade against McCain even after other Republicans demanded he apologize and clarify his remarks.

"He is yet another all talk, no action politician who spends too much time on television," Trump posted on Facebook after the Iowa summit, "and not enough time doing his job and helping the Vets."