President Donald Trump’s decision to pave the way for a Turkish invasion of northern Syria at the expense of Kurdish allies in the region has infuriated Republican allies in the Senate who have spent the last two weeks twisting themselves in knots to defend him from an impeachment inquiry.

Late on Sunday, the White House released a one-paragraph statement declaring that a Turkish invasion of northern Syria was imminent, and the United States would “not support or be involved in the operation” and “will no longer be in the immediate area.” For Kurds in the region—who have been fighting ISIS with U.S.-supplied weapons and are largely considered the strongest fighting force in Syria—the declaration amounts to an abrogration of agreements with the United States to defend them against Turkey, which considers them to be terrorists. In June, Trump himself warned that abandoning the alliance would allow Turkey to “wipe out the Kurds, who helped us with ISIS.”

The backlash from his Republican allies was swift.

Sen. Lindsey Graham (R-SC), led the way on Monday morning, with the South Carolina senator calling the move “shortsighted and irresponsible” on Fox & Friends, a show that effectively serves as a televised presidential daily brief for Trump.

“This impulsive decision by the president has undone all the gains we’ve made, thrown the region into further chaos, Iran is licking their chops, and if I’m an ISIS fighter, I’ve got a second lease on life,” Graham said. “I will do everything I can to sanction Turkey’s military and their economy if they step one foot into Syria. I hope I’m making myself clear how shortsighted and irresponsible this decision is.”

Graham even referenced the House’s impeachment inquiry, unprompted, before adding that while “I’ve tried to help him,” the president’s behavior was “just unnerving to its core.”

Graham, who has spent years trying to steer Trump closer to the hawkish foreign policy stances held by his Republican predecessors, opened the floodgates for Republicans who see Trump’s move as a threat to a critical U.S. ally in the region, and a potentially disastrous embrace of an autocratic regime.

Indeed, Monday saw widespread pushback from around the Senate GOP, from lawmakers who’ve cozied up to Trump to those who have been more willing to call him out. Sen. Marco Rubio (R-FL), a Trump ally who has nudged him toward more hawkish positions on Venezuela and Iran policy, called the decision “a grave mistake that will have implications far beyond Syria.” Sen. Cory Gardner (R-CO) said that he was “deeply concerned” that the decision could leave Kurds who risked their lives to fight ISIS in harm’s way.

And Sen. Mitt Romney (R-UT), probably Trump’s most vocal Senate GOP critic, characterized the pullout as “a betrayal” that “presages another humanitarian disaster” in Syria. Romney went so far as to join Sen. Chris Murphy (D-CT) to demand that administration officials explain their move to lawmakers and the public. Sen. Ben Sasse (R-NE), meanwhile, has toned down his Trump criticism lately but warned that the retreat would “likely result in the slaughter of allies who fought with us, including women and children.”

Sen. Susan Collins (R-ME) managed to subtweet the president, calling Trump’s move “a terribly unwise decision” moments after the president described his wisdom on the matter as “great and unmatched.”

Even Majority Leader Mitch McConnell, in a rare rebuke of the president whom he has pledged to protect from removal from office, pleaded with Trump to maintain an American presence in the region and to prevent Turkey from invading.

“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 said in a statement.

Major new conflict between Turkey and our partners in Syria, McConnell said, “would seriously risk damaging Turkey’s ties to the United States and causing greater isolation for Turkey on the world stage.”

Among Trump’s allies seeking to thread the needle between opposing the withdrawal and ensuring that the president didn’t feel attacked was Sen. Ted Cruz, who tweeted that while Trump was “right to want to bring our soldiers home,” it would be “DISGRACEFUL” (capital letters Cruz’s) to allow Turkey to attack Kurdish allies in the region.

“Our enemies and rivals (Iran, Russia, etc.) don’t abandon their allies,” Cruz said. “If we want allies to stand with America in the future, we shouldn’t either. Honorable nations stand by their friends.”

Seemingly alone among Senate Republicans in supporting the withdrawal was Sen. Rand Paul, who is perhaps the biggest cheerleader of Trump’s isolationist instincts. The Kentucky senator told reporters that he stands with Trump “as he once again fulfills his promises to stop our endless wars and have a true America First foreign policy.”

Other Senate Republicans have remained tight-lipped on the president’s decision, perhaps praying that Trump will reverse course on the withdrawal—as he did in December 2018, after sharp rebukes from within the party and the resignation of Secretary of Defense Jim Mattis halted a hastily announced drawdown of U.S. troops from Syria.

Asked during an event celebrating a trade agreement with Japan on Monday afternoon about whether he had consulted with the Joint Chiefs of Staff about the decision, Trump insisted that he had.

“I consulted with everybody,” Trump said.

Additional reporting: Sam Brodey