By Misha Euceph

With Donald Trump leading by a mile on the eve of the South Carolina primary, his rivals are asking whether he is a true Republican.

A super PAC aligned with former Florida governor Jeb Bush put it bluntly in a new ad: “If Trump wins, conservatives lose.”

“Donald Trump is just plain wrong,” declares an ad by Texas Sen. Ted Cruz. The 30-second spot criticizes Trump for speaking highly of Planned Parenthood’s efforts on women’s health, even as the New York businessman says he opposes abortion.

Conservative critics say Trump,  a former Democrat, is a flip-flopper, yet the charge has been slow to stick. He easily won last week’s New Hampshire vote and holds a substantial lead in the polls ahead of Saturday’s GOP primary. FiveThirtyEight gives him an 84 percent chance of winning the state.

All candidates massage their records, but the charge of changing positions can doom a campaign, most notably Democrat John Kerry in 2004. He never recovered from his statement that he voted for an Iraq War measure before he voted against it.

But evidence that Trump has traded liberal views for conservative ones does not much matter to his most enthusiastic supporters.

“We evolve. That’s the great thing about America,” said former army Capt. Aunisa Strokland at an Iowa rally. “You have the right to believe in anything you want to believe in at a given point. I don’t believe in things I used to believe in five years ago.”

Strokland defended Trump’s switch on abortion. In 1999, he said, “I believe it is a personal decision that should be left to the women and their doctors.” Twelve years later, addressing the Conservative Political Action Conference, he said, “I am pro-life.”

“It’s not a major thing with me,” said Raekwon Goodlet, a young, black voter from Iowa, of the abortion issue. “It doesn’t bother me. There are a lot of people that have a change of heart.”

Trump’s campaign website bypasses the issue of abortion, focusing instead on issues including tax reform, immigration reform and Second Amendment gun rights. Yet these issues, too, fail to pass a consistency test.

“I support the ban on assault weapons and I support slightly longer waiting periods to purchase a gun,” said Donald Trump in 2000 in his book, The America We Deserve.  At the CPAC conference eleven years later, however, Trump flipped on the issue, declaring, “I am against gun control.”

Trump’s change in party affiliation — he was a registered Democrat from 2001 to 2009, according to the New York City board of elections— doesn’t give his supporters pause, either. Instead, some claim to make the switch with him.

“I used to be the same. Because of him, I’m now a Republican,” said Mike Nelson.

Others laud Trump’s willingness to entertain conflicting ideas. “I think it’s nice that he has views from both sides,” says Dakota Johnson, an 18-year-old Trump supporter in Iowa.

So far, Trump’s success stands in stark contrast to John Kerry’s in 2004. The Democratic nominee faced repeated attack ads. One showed him windsurfing, tacking back and forth, as it hammered the  point home.

“No other Republican candidate would have lasted with a quarter of the things he’s saying, but he gets away with it,” said University of Iowa politics professor Timothy Hagel.

Hagel noted that Trump not only changes his position  over time, but quickly pivots in certain contentious situations. He recalled a derogatory comment the candidate made about opponent Carly Fiorina’s appearance, only to declare, “She’s beautiful,” without apologizing at the following GOP debate.

“He’s a master manipulator,” Hagel said.

Other scholars point to the strategy of Trump’s opponents as the reason the “flip flopper” label never stuck. “The attack has not been made in a very direct or sustained way,” said Cary Covington, a scholar of the presidency at the University of Iowa .  “It did not show up early, when voters were still forming their opinions.”

Covington said the window to influence a voter is short.

“Once voters form an opinion, they resist changing it,” he added. “Because of cognitive dissonance, they tend to discount the source of the attack or even just ignore it, rather than allowing it to change a more fundamental position that they’ve formed.”

Sue and Stan Gustafson, husband and wife, are unbothered by Trump’s shifts. In his move to the right, Sue says, they see themselves, “We were hippies in the 70s. He used to be pro-choice. People change. We’re totally different. You get older, you get wiser.”