“This gives evangelicals pause because now they’re wondering, ‘Hmm, that was not a good move. What’s next? Does this mean he’s going to throw Israel under the bus if he threw the Kurds under the bus?’” a longtime friend of the president said. Another evangelical Trump ally told the president he was offended by a comment the president made about Kurdish fighters having “plenty of sand to play with,” according to a person briefed on the conversation.

It’s a first for Trump’s presidency: The same evangelical leaders who’ve been notoriously unmovable through prior controversies have spoken out forcefully to condemn his policy toward Syria. Televangelist Pat Robertson said Trump was “in danger of losing the mandate of heaven.” Family Research Council head Tony Perkins described the move as “inconsistent with what the president has done” previously.

Former Arkansas Gov. Mike Huckabee shake hands with then-Republican presidential candidate Donald Trump. | Christopher Furlong/Getty Images

“I was concerned about it, but feel more confident after talking with POTUS and seeing the results of the cease-fire and the economic sanctions,” former Arkansas Gov. Mike Huckabee, who initially blasted Trump’s decision to ditch the Kurds as a “huge mistake,” wrote in an email to POLITICO on Tuesday. (In remarks from the White House Diplomatic Reception Room less than 24 hours later, Trump announced he would be lifting those same economic sanctions against Turkey — remarks that came a day after the U.S. special envoy for Syria engagement told a Senate panel the Turkish military offensive had killed hundreds of Kurdish fighters.)

The outrage over Trump’s Syria decision, combined with the growing threat of impeachment, has left the president facing a new test in his relationship with white evangelicals as signs of tensions have begun to surface in recent polls. For some, his culturally conservative agenda may not be enough to keep them from walking away if the situation in Syria deteriorates further.

It’s a dilemma that has left Trump’s biggest religious boosters asking themselves whether his sky-high support with so-called values voters will last through next November.

“If he’s going to win in 2020,” said the longtime Trump friend, “he has to be north of the 81 percent [of white evangelicals] he won in 2016. I’m not suggesting that the polling is all of a sudden going to show that his support is plummeting because of Syria. But if it stays stagnant, he’s a one-term president.”

White evangelicals have long grappled with a president they consider their greatest champion since the Reagan years, but who rarely approaches policy matters or discourse with their preferred tone or moral code. They have asked Trump not to curse at his campaign rallies, despite standing by him when he was caught on tape making vulgar comments about women in 2016. They have endorsed his hard-line immigration policies, but privately urged him to ditch the harsh language about immigrants and refugees. And they have consistently cited his appointment of anti-abortion judges as a hallmark of his presidency without mentioning the uncomfortable moment when, as a candidate, he suggested punishing women who choose to end their pregnancies.

Now, the president’s evangelical allies are pressing him to consider the consequences of pulling troops from Syria, which he has cast as a financially sensible decision. And they are warning him of trouble ahead if he doesn’t — both in the region, where U.S.-backed Kurdish fighters have been killed by Turkish airstrikes in recent days, and with his political standing back home.

“This is a danger zone for this administration when it comes to evangelicals. They see religious persecution, Iran gaining a foothold, Israel facing threats and the possibility of ISIS reemerging, and what Trump keeps talking about is the land, and the money, and the deal-making,” said the longtime Trump friend. “The moral compass is missing, and he’s off balance here with evangelicals.”

Unlike other voting blocs that have slowly moved away from Trump, white evangelicals have displayed a certain level of elasticity in their support for him — opting to adapt to the worst moments and elements of his presidency, even when they have shown initial signs of shock.

“He’s a blue-chip stock for evangelicals and they’re cashed in fully. If there’s fluctuation in the market, they always ride it out,” said the Trump pal.

It’s an enduring mystery of the Trump era and one that prompts questions about tribalism and the state of both major political parties. Do white evangelicals stand by Trump because there is no suitable Republican or Democratic alternative? Or do they embrace him because that’s what they’ve seen the most prominent among them do?

“My gut says white evangelicals will jump when and if Fox News does,” said Elesha Coffman, a scholar of American religion at Baylor University. “Any movement, if we see it, isn’t going to come from within their religious communities.”

A lengthy study released this week by the Public Religion Research Institute offers other clues about the current state of Trump’s relationship with white evangelical voters, as well as why it could change between now and Election Day. In striking terms, the survey captures just how substantial the president’s support is among white evangelicals: 99 percent of GOP-leaning white evangelical Protestants oppose impeaching and removing Trump from office and 63 percent say he has done nothing to damage the dignity of the presidency, separating them from majorities across all other major religious groups that said he has.

Other figures raise questions about the durability of white evangelicals’ support for Trump, particularly given the precarious position he finds himself in with Syria.

For example, 63 percent of white evangelical Protestants in the PRRI study said terrorism is a major concern for them — more than immigration (55 percent), which has been Trump’s single biggest issue, or health care (53 percent). Those figures come amid warnings that the U.S. pullout from Syria could rekindle terrorism in Europe and cause a resurgence of the Islamic State. Already, a separate NPR/Marist survey found that nearly 30% of white evangelicals believe U.S. security has been weakened by Trump.

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The worse the situation becomes in Syria the more comfortable white evangelicals might feel about distancing themselves from Trump, Coffman said. That happened gradually during the Watergate era, when rank-and-file evangelicals slowly walked away from President Richard M. Nixon.

After the Syria cease-fire, “will things get much worse? Will we get pictures of children who get victimized by chemical weapons? Will there be enough of a rebuke from Republicans or more voices inside white evangelicalism speaking out about this?” Coffman asked, adding that “it’s possible we’ll see movement then, but I wouldn’t bet on it.”

There is also the shadow that impeachment has cast over Trump’s presidency, and how white evangelicals are responding.

A much-discussed Fox News poll found that nearly three in 10 white evangelicals want the president impeached and removed from office — a figure that startled some officials on Trump’s 2020 campaign, according to an outside adviser. And in the NPR/Marist survey, which was taken after House Democrats began their impeachment inquiry, only 62 percent of white evangelicals said they definitely plan to vote for Trump next fall.

That’s the number Trump’s top evangelical supporters are closely monitoring and cautioning the president not to ignore. Eighty-one percent of the white evangelical vote in 2016 was enough to carry him to the White House, they say, but with underwater approval ratings among other key constituencies he needs to do even better next fall.