President Donald Trump's decision to withdraw U.S. troops from Syria has drawn the ire of one of his usual allies: Lindsey Graham.
The Republican senator from South Carolina first blasted Trump on Twitter, writing that the withdrawal of the roughly 2,000 U.S. troops in Syria "would be a huge Obama-like mistake."
In a statement, Graham expanded upon his tweet, writing, "While American patience in confronting radical Islam may wane, the radical Islamists’ passion to kill Americans and our allies never wavers."
He added, "An American withdrawal at this time would be a big win for ISIS, Iran, Bashar al Assad of Syria, and Russia. I fear it will lead to devastating consequences for our nation, the region, and throughout the world."
Graham serves on the Senate Armed Services Committee. He is often one of the president's fiercest defenders on Capitol Hill, speaking in support of the president during controversial moments like the revocation of former CIA Director John Brennan's security clearance and the nomination of Supreme Court Justice Brett Kavanaugh.
Trump hinted at his decision about removing U.S. troops from Syria in a tweet.
"We have defeated ISIS in Syria, my only reason for being there during the Trump Presidency," he said.
Graham tweeted that declaring victory over the Islamic State is premature: "With all due respect, ISIS is not defeated in Syria, Iraq, and after just returning from visiting there--certainly not Afghanistan."
In the halls of the Senate, Graham told ABC News he will be meeting with Defense Secretary James Mattis and called for a hearing on the decision. In another jab at Trump, he said that foreign policy can't be determined over a tweet.
"I want a hearing. I want oversight. This is a Republican president who I try to work with and I like him but he can’t be immune from oversight," Graham said.
Graham isn't alone in his criticism of the president. He was one of several senators who expressed their discontent to Vice President Mike Pence at a Republican luncheon.
Sen. Susan Collins of Maine told reporters that they had a "lengthy" discussion about the decision to pull troops out of Syria.
Sen. Bob Corker, who is the chairman of the Senate Foreign Relations Committee and a frequent critic of the president, headed to the White House Wednesday afternoon to talk to Trump.
The senator from Tennessee told reporters that he thought Trump just "woke up" and made the decision.
The meeting between Corker and Trump had reportedly been scheduled before the Syria news broke but the senator hoped to ask the president about the administration's move to send troops home. While at the White House, Corker was reportedly informed that his meeting with Trump had been cancelled.
Earlier today, Rep. Adam Kinzinger, R-Ill., pushed back on the president's declaration of victory over ISIS, tweeting, "This is simply not true."
Florida Sen. Marco Rubio told ABC News that Trump's advisers did him a "terrible disservice."
"This is a colossal, in my mind, mistake. A grave error. This is going to have significant repercussions in the years and months to come," Rubio said.
In a video posted to his Facebook page, Rubio said, "I believe the decision that was made today is a grave error that's going to have incredible consequences that potentially have not been fully thought through."
Kentucky Sen. Rand Paul said he supported the president's decision.
"We have a president with the courage to declare victory and bring the troops home," Paul said.
He added, "I think it takes courage to do this because there are a million naysayers on both sides of the aisle who always want to remain."
ABC News' Luis Martinez, Elizabeth McLaughlin and Mariam Khan contributed to this report.