NORTH AUGUSTA, S.C. >> Mark Jebens, a veteran of 22 years in the Marine Corps, found no fault with Donald Trump’s scathing criticism that President George W. Bush “lied” about weapons of mass destruction while leading the United States into war in Iraq.

“At the end of the day, a lot of good Marines and sailors and airmen died over something that wasn’t there,” said Jebens, who served three combat tours in Iraq. “So you’ve got to ask tough critical questions. In the military we called it a debrief or a hot wash.”

Trump’s hot wash of Bush in a debate on Saturday, including a suggestion that he did not heed intelligence warnings before the Sept. 11, 2001, terrorist attacks, convinced many Republicans that Trump had finally gone too far, tarring a former president who is popular in military-friendly South Carolina, and uttering charges that Rush Limbaugh, for one, called “liberal Democrat lingo.”

But numerous military veterans interviewed at Trump rallies in South Carolina this week, including Jebens, said they had no problem with Trump’s comments, even if they did not entirely agree with him.

At the same time, the stubborn popularity of Trump, who defies Republican orthodoxy on issue after issue, shows how deeply the party’s elites misjudged the faithfulness of rank-and-file Republicans to conservatism as defined in Washington think tanks and by the party’s elected leaders.

The dichotomy is particularly vivid here in South Carolina, the most conservative state on the nominating calendar so far, where Trump holds a double-digit lead over his closest rivals in the latest polls.

“In a lot of senses Republicans have overestimated how much dedication to ideology was motivating their voters,” said Ben Domenech, publisher of The Federalist, a conservative online journal.

“The people who are supporting Trump represent a significant portion of the Republican base, which has always been less ideological and more about trust of the person,” Domenech said. “It is something both the Republican leadership in Washington and conservative ideological elites have underestimated.”

At a rally Tuesday in North Augusta, S.C., across the Savannah River from Georgia, Trump called to the stage a man from the audience who had quieted a protester in the crowd.

“I did two tours in Iraq,” the man said, as the crowd erupted in cheers and chants. “If it weren’t for Mr. Trump right here, I don’t think any of us would have the voice that we have.”

Rival Republican candidates have long criticized Trump for once holding liberal views on matters like abortion. And conservative commentators have exposed his apostasy on issues like free trade and entitlements.

But nowhere was his break with the party’s orthodoxy more vivid than in the debate last Saturday in South Carolina, a week before Republicans hold their primary here. Besides attacking the former president, while the audience booed loudly, Trump asserted that, abortion aside, Planned Parenthood did “wonderful things” for women’s health.

Sen. Ted Cruz of Texas, who last year threatened to shut down the federal government over funding Planned Parenthood, and who has been hoping to carve evangelical support away from Trump, quickly went up with a negative ad about Trump’s support for the group.

But many people at his rallies agreed with Trump on the issue. “I oppose abortion, but I think Planned Parenthood does a lot of good for people who can’t afford birth control,” said Kim Wells, a schoolteacher and Trump supporter in North Augusta.

At a rally in Louisiana last week, Trump rejected attacks from Jeb Bush and other candidates that he was not a conservative. He dismissed ideological labels altogether, a sentiment endorsed by the 10,000 people in the arena, who thundered their approval over and over. Instead of calling himself conservative, Trump said, “I’m a guy with common sense that’s going to make us a fortune.”

Trump’s populism, a combination of economic nationalism that favors protectionism and a strongman approach to foreign countries that is also noninterventionist, defies almost everything Republicans in Washington have stood for, drawing scorn from party leaders and opinion makers.

While Republican business leaders and their lobbying groups push for free trade, Trump has rallied thousands by promising to slap 35 percent tariffs on imported goods made by U.S. companies that move factories abroad.

“I’ve been through the racks in Kmart trying to find a union label,” said Bob Mason, a retired Postal Service letter carrier who lined up to hear Trump here Tuesday. “If companies want to go overseas, let them stay over there and keep their products over there,” he said. “If they want American money, they ought to build a company here.”

Trump’s decision to seize on immigration as his signature issue has showed how out of step the Republican establishment is with rank-and-file voters. Trump’s call to deport more than 11 million undocumented people in the country, denounced as impossible and inhumane, has substantial support. One in four voters in a New York Times poll last year said illegal immigrants should be required to leave the country.

Exit polls from the New Hampshire primary, which Trump won decisively, showed 65 percent of Republicans supported his call for a temporary ban on Muslims entering the United States.

“He says what everyone else wants to say, but they’re too scared to say,” said Steve Moody, a small-business owner at Trump’s rally on Tuesday. “Illegal immigrants are coming into this country that we are steadily paying for day after day.”

Keith Hutto, a plumbing contractor who attended the rally with Moody, blamed George W. Bush for the housing bust and financial crisis that occurred during his second term. “My business in 2006, halfway through, it got bad,” Hutto said. “We kept the doors open and all, but right into 2008 and even into 2010, it was tough.”

A CNN/ORC poll of South Carolina released Tuesday showed Trump with a 16-point lead over Cruz, his closest rival. Sen. Marco Rubio of Florida and Jeb Bush occupied a third tier.

Most surprising, perhaps, is that Trump led Cruz by 20 percentage points among evangelical voters, whose support Cruz rallied to win the Iowa caucuses this month.

The poll showed Trump losing supporters after the debate on Saturday, with 40 percent supporting him before and 31 percent afterward.

Another pollster, David Woodard of Clemson University, said his survey of Republicans showed Trump’s support holding steady after the debate.

“Even after Trump’s debate performance, with all the dysfunctional behavior — the next day his numbers were the same as before the debate! Go figure,” he said in an email.

Hogan Gidley, a former executive director of the South Carolina Republican Party, whose roots are in the evangelical community, said the Republican base was angry about sending politicians with impeccable conservative credentials to Washington, but seeing nothing change there.

“All us rank-and-file conservatives have been dictated to from Washington, D.C., for decades, and we’re sick of it,” Gidley said. “I don’t need a candidate to come from our ranks. I need a candidate who’s not going to lie to me.”

Trump, who is not taking large donations from special interests, fits that bill for many people, he added.

“The voters are furious,” Gidley said, “and they’re not letting a stump speech sway their vote.”