Donald Trump escalated his feud with Sen. John McCain on Saturday in Iowa by suggesting it was only his capture and five years as a prisoner of war which turned him into a 'war hero.'

And in seconds flat, his passive Republican primary opponents who had been playing a wait-and-see game with his rise in the polls turned on him.

'He is not a war hero,' Trump sniped about McCain, drawing a mixture of boos and nervous laughter at the Family Leader Summit in the university town of Ames.

'He is a war hero because he was captured. I like people that weren't captured, OK? I hate to tell you,' Trump said.

And moments later: 'I believe perhaps he is a war hero.'

McCain, a Navy pilot, spent years in a Viet Cong prison after his plane was shot down over Hanoi in October 1967. He broke both of his arms and legs after ejecting from his aircraft, and was later tortured enough to produce permanent physical disabilities.

He received the a Purple Heart, a Silver Star and the Distinguished Flying Cross.

Trump got student and medical deferments and never served in uniform.

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FEUDING: Trump attacked Sen. John McCain and said the only reason he is considered a war hero is his capture and imprisonment as a POW during the Vietnam War

NOT A HERO? Sen. John McCain spent more than five years in a North Vietnamese prison after his plane was shot down during the Vietnam War

WALKING WOUNDED: McCain's torture left him disfigured and permanently disabled. He's pictured being greeted by then-President Richard Nixon upon his release in 1973

OLD NEWS: Sen. Al Franken, pictured this month at a Senate hearing, said in 2000 when McCain was a presidential primary candidate that he had 'sat out the war' as a POW. 'I don’t buy the war hero thing. Anybody can be captured,' he wrote

He told reporters after his speech that a bone spur in his foot led to the medical exemption from the draft. Asked which foot had disqualified him, he couldn't remember.

'You'll have to look it up,' Trump said dismissively in a concrete room underneath Stephens Auditorium at Iowa State University. 'It's in the records.'

He is not a war hero. He is a war hero because he was captured. I like people that weren't captured, OK? Republican presidential candidate Donald Trump criticizing Sen. John McCain on Saturday

Sen. Al Franken, a Minnesota Democrat and a former comedian, famously said something in 2000 that was similar to what brought Trump heartburn on Saturday.

'I doubt I could cross the line and vote Republican,' he told Salon then. 'I have tremendous respect for McCain but I don’t buy the war hero thing.'

'Anybody can be captured,' said the famously liberal Franken. 'I thought the idea was to capture them. As far as I’m concerned he sat out the war.'

Franken's comments did not lead to public controversy because he wasn't yet in electoral politics. He won his senat

Rick Perry, the former Texas governor who is running 10th in an average of national polls, immediately called for Trump to quit his presidential campaign.

Former Florida Gov. Jeb Bush called the attack 'slanderous.'

And the Republican National Committee issued the billionaire a stern rebuke.

'I respect Sen. McCain because he volunteered to serve his country,' Perry said in a statement. 'I cannot say the same of Mr. Trump.'

'His comments have reached a new low in American politics. His attack on veterans make him unfit to be Commander-in-Chief of the U.S. Armed Forces, and he should immediately withdraw from the race for President.'

I have tremendous respect for McCain but I don’t buy the war hero thing. Anybody can be captured. I thought the idea was to capture them. As far as I’m concerned he sat out the war. Democratic Sen. Al Franken on McCain in 2000

Appearing on the same stage where Trump spoke hours earlier, Perry said in the late afternoon that his rival's words left him feeling unsettled.

'I was highly offended at what Donald Trump said about John McCain and his years of sacrifice in a dirty, singy prison in North Vietnam,' Perry said.

Trump 'doesn't understand' the U.S. military 'or doesn't care,' he added, and he 'owes every single American veteran, and in particular John McCain, an apology.'

'You may disagree with his policies,' he scolded Trump about McCain, 'but don't question the men and women of our military.'

Asked by moderator Frank Luntz whether Trump's comments should disquality him as a presidential candidate, Perry nodded.

'And as the commander-in-chief of this country,' he said. 'In one word: Yes.'

Former Florida Gov. Jeb Bush vented on Twitter, saying: 'Enough with the slanderous attacks. @SenJohnMcCain and all our veterans – particularly POWs have earned our respect and admiration.'

And Scott Walker, according to a Washington Post report, told reporters in Sioux City, Iowa that Trump 'needs to apologize to Senator McCain and all the other men and women who have worn the uniform.'

'It's just a disgrace,' he said.

DON'T LET THE DOOR HIT YOU! Former Texas Gov. Rick Perry said Donald Trump should leave the presidential race in the wake of his controversial comments about Sen. John McCain

'SLANDEROUS': Former Florida Gov. Jeb Bush jumped on the bash-Trump bandwagon and panned his surprising shot at McCain

RNC Communications Director Sean Spicer said in a statement that McCain 'is an American hero because he served his country and sacrificed more than most can imagine. Period.'

'There is no place in our party or our country for comments that disparage those who have served honorably,' Spicer said.

DailyMail.com spoke with Trump campaign manager Corey Lewandowski by telephone as the real estate mogul's private jet was about to take off.

Lewandowski downplayed the controversy and said criticizing McCain shouldn't be off-limits.

'Oh, come on,' he said. 'John McCain has had 30 years to do right by American veterans. He's been on the committees. And he's done nothing.'

Lewandowski seemed surprised to learn that his fellow Republicans and the RNC had begun to gang up on him.

Asked if it was a big deal that Trump's GOP rivals smell blood in the water, he replied: 'It's not.'

Speaking with reporters in between a book-signing and his speech, Texas Gov. Ted Cruz praised McCain but refused to join in the anti-Trump pummelling.

'I respect and admire him,' he said of the Arizona senator. 'He is an American war hero.'

But 'I recognize that folks in the press love to see Republican-on-Republican violence,' he complained. 'And so you want me to say something bad about Donald Trump ... I'm not going to do it.'

'John McCain is a friend of mine. I respect and admire him and he's an American hero. And Donald Trump is a friend of mine. The rest of it – you guys can throw rocks at Republican candidates. I'm not going to engage in that process.

Asked again if he would denounce Trump, Cruz insisted: 'I ain't gonna do it.'

He ended his press availability abruptly and made a brisk exit toward the VIP area of the theatre while DailyMail.com asked: 'What would he have to do, for you to denounce him?'

NOT GOING THERE: Former Arkansas Gov. Mike Huckabee (left) and Texas Sen. Ted Cruz (right) refused to pile on Trump but praised McCain as an American institution and a war hero

IN DENIAL? Trump's campaign has tried to clarify his comments but hasn't apologized to McCain

Interviewed steps away, former Arkansas Gov. Mike Huckabee also declined to call for Trump's ouster from the Republican primary, but defended McCain forcefully.

'Well, John McCain is a hero,' he told DailyMail.com. 'Simple as that – and I ran against him in 2008.'

'I walk on free ground every day because of men like Senator McCain.'

Trump focused considerable rhetorical artillery on the Arizonan on Saturday, mocking his bona fides on military and veterans issues:

'He graduated last in his class at Annapolis,' he claimed. 'Well, second-to-last.'

In a press conference following his speech, Trump backtracked a few inches about prisoners of war.

'If somebody's a prisoner, I would consider him a war hero,' he said. 'But we have lots of heroes who weren't prisoners.'

'I like the people that don’t get captured, and I respect the people that do get captured,' he said later in the contentious 18-minute huddle attended by more than 60 reporters.

But he mostly engaged in a verbal push-and-shove with scribes who demanded answers about his tough talk against McCain.

To one insistent journalist who badgered him with question after question, Trump snapped: 'Go back to being a pundit.'

'John McCain has not done enough for the veterans,' Trump said, pivoting away from his incendiary words.

'The veterans in this country are suffering. The veterans in this country are treated as third-class citizens. John McCain talks a lot, but he doesn’t do anything.'

LASTING EFFECTS: Torture in a North Vietnamese prison left McCain unable to fully use his right arm and hand. He's shown in 2013 with the UK's Prince Harry

The $10 billion man was otherwise a crowd favorite in Ames, Iowa, speaking about his religion before a group of Christian conservatives

Anti-abortion politics were visible in Ames, Iowa on July 18, 2015 at the Family Leader summit, a gathering of Republican presidential candidates hosted

The billionaire's tussle with McCain began after he drew a reported 15,000 people to a campaign event in Phoenix to talk about illegal immigration.

McCain, a proponent of comprehensive immigration reform, called his audience 'crazies.' Trump responded that the GOP's 2008 presidential nominee was a 'dummy.'

In an emailed statement to DailyMail.com, Trump said after his press conference: 'I am not a fan [of] John McCain because he has done so little for our Veterans and he should know better than anybody what the Veterans need, especially in regards to the VA.'

'He was extremely disrespectful to the thousands upon thousands of people, many of whom happen to be his constituents, that came to listen to me speak about illegal immigration in Phoenix last week by calling them "crazies",' Trump carped.

'These were not "crazies" – these were great American citizens.'

'I have great respect for all those who serve in our military including those that weren’t captured and are also heroes,' he insisted.

Republicans auditioned all day for Christian conservatives, parading their bona fides in the nations' first presidential primary state. But not everyone searching for votes showed up.

The cattle-call brought nine of the Republican Party's 15 declared presidential candidates to a single stage, less than a day after Democrats did the same thing – with all five of their White House hopefuls – a two-hour drive to the east.

The Christian-right sponsoring group, The Family Leader, attracted mostly the candidates from the conservative end of the GOP spectrum.

Led by political kingmaker Bob Vander Plaats, the group wields outsize influence in the Hawkeye State whenever Republicans barnstorm through during the run-up to the quadrennial Iowa caucuses.

Donald Trump's childhood church was First Presbyterian Church in Jamaica, Queens, New York City. He said he was in church just last week

Missing in Ames was the Republican front-runner Jeb Bush, the sometimes-moderate New Jersey governor Chris Christie and the usually moderate former New York governor George Pataki.

Nowhere to be found was senator Rand Paul of Kentucky, whose libertarian brand of Republicanism, makes some religious conservatives wary.

Carly Fiorina, the GOP's only female While House contestant, also didn't make the trip.

Florida Sen. Marco Rubio, the day's first candidate-speaker, wrapped up his time on stage in a Q&A with pollster Frank Luntz by asking if he could read aloud from a book.

'It's a Bible,' he said, drawing wild cheers from the audience.

He read from the Gospel of Luke, chapter 12, verse 48: 'From everyone who has been given much, much will be demanded' – explaining it as a parable about America's global primacy and its obligations to keep its people, and the world, safe.

Rubio blasted the Obama administration's recent nuclear bargain with Iran, calling it 'a complete sham.'

He also castigated the president for sidestepping the role of Islam in global terror.

A lingering resentment was visible on Saturday over this month's stunning Supreme Court decision legalizing same-sex weddings nationwide. 'Marriage = 1 [man] and 1 [woman],' a projected image declared above the stage as the crowd filed in, using icons to represent male and female

'It's not radical Presbyterian terrorism,' he said. 'It's radical Islamic terrorism. ... We have to target them militarily in their safe havens.'

Abortion politics were visible both outside and inside the event venue in Ames, Iowa.

Sign-wavers pointed to right-wing outrage over a surreptitious video that showed a Planned Parenthood medical doctor describing how she tailored her abortion procedures in order to preserve fetal body parts for human biologics companies.

Iowa Rep. Steve King kicked off the day with anger over 'that in-quotes "doctor"' whom he said was killing 'babies that could be viable outside the womb. It is sickening to watch.'

Seizing on the political moment as a springboard for new laws tightening abortion restrictions, King said: 'This is our chance.'

'We should cut off every penny of taxpayer funds' to the organization, Cruz declared during his remarks on stage.

That comment drew the day's first spontaneous standing ovation; the senator stood and applauded the idea too.

He got a second standing ovation during a discussion of same-sex marraige for declaring that 'we will take this country back, for our values.'

A third erupted when he pledged to revoke 'every single unconstitutional executive action Barack Obama has done.'

A lingering resentment was visible on Saturday over this month's stunning Supreme Court decision legalizing same-sex weddings nationwide.

'Marriage = 1 [man] and 1 [woman],' a projected image declared above the stage as the crowd filed in, using icons to represent male and female.