President Trump surprised many when he announced late Sunday night his decision to pull back US troops from northern Syria, saying they would step aside for an expected Turkish attack on Kurds who have fought alongside Americans for years.

Perhaps even more surprising has been the blowback he’s received from loyal Republicans who have staunchly defended him through other controversies, including the impeachment inquiry currently gathering momentum against him.

Here’s a look at which influential Republicans are opposing Trump on the Syria matter.

Senator Lindsey Graham

The South Carolina Republican, who has been among Trump’s most vocal defenders, called the Syria decision ‘‘a disaster in the making’’ that would throw the region into chaos and embolden the Islamic State group.


‘‘I hope I’m making myself clear how short-sighted and irresponsible this decision is,’’ Graham told Fox News. ‘‘I like President Trump. I’ve tried to help him. This, to me, is just unnerving to its core.’’

He also sent a long tweet thread condemning the plan.

Senator Marco Rubio

The Florida Republican, who has shrugged off the key allegation in the impeachment inquiry — that Trump pressured foreign powers to investigate a top Democratic rival — tweeted that Trump’s shift on Syria is ‘‘a grave mistake that will have implications far beyond Syria.’’

Senator Susan Collins

The moderate Republican from Maine, who has been more willing than many Republicans to condemn Trump’s calls for foreign intervention in the 2020 election, called the Syria move ‘‘a terribly unwise decision’’ that would ‘‘abandon our Kurdish allies, who have been our major partner in the fight against the Islamic State.’’

Senator Mitt Romney

The former Massachusetts governor and current Utah senator cast Trump’s announcement as ‘‘a betrayal.’’

‘‘It says that America is an unreliable ally; it facilitates ISIS resurgence; and it presages another humanitarian disaster,’’ Romney tweeted.


Romney also released a joint statement with Senator Chris Murphy, a Connecticut Democrat, condemning the move.

“The President’s decision to abandon our Kurdish allies in Northern Syria in the face of an assault by Turkey is a betrayal that will have grave humanitarian and national security consequences,” the statement said.

Nikki Haley

Haley, the former South Carolina governor who was Trump’s hand-picked ambassador to the United Nations, also cast the decision to withdraw US troops from northern Iraq as a betrayal of a key ally.

‘‘The Kurds were instrumental in our successful fight against ISIS in Syria. Leaving them to die is a big mistake,’’ she wrote on Twitter.

Senate Majority Leader Mitch McConnell

While a number of Republicans criticized Trump’s decision, one of their most important leaders was sanguine, at first offering little concern about Syria or impeachment during an appearance at the University of Kentucky.

But after the appearance, McConnell issued a statement warning that Trump’s proposed withdrawal ‘‘would only benefit Russia, Iran, and the Assad regime. And it would increase the risk that ISIS and other terrorist groups regroup.’’

“I urge the president to exercise American leadership to keep together our multinational coalition to defeat ISIS and prevent significant conflict between our NATO ally Turkey and our local Syrian counterterrorism partners,” McConnell wrote in the statement. “Major new conflict between Turkey and our partners in Syria would seriously risk damaging Turkey’s ties to the United States and causing greater isolation for Turkey on the world stage.


‘‘As we learned the hard way during the Obama Administration, American interests are best served by American leadership, not by retreat or withdrawal,’’ McConnell said.

Jaclyn Reiss of the Globe staff contributed to this report.