Sen. Bob Corker (R-TN), the chairman of the Senate Foreign Relations Committee, warned on Wednesday that President Donald Trump will “absolutely” withdraw the United States from the Iran nuclear deal in less than a month.

“I think many of the people around the president… would like to see a framework agreement achieved. I think that’s a better outcome for our nation both in the short and long-term,” Corker told The Daily Beast.

“I don’t think there’s any doubt at all” that Trump will pull the U.S. out of the agreement, the senator said earlier at a Christian Science Monitor breakfast with reporters.

The comments, which come just weeks ahead of the May 12 deadline for the U.S. to certify the terms of the Obama-brokered nuclear agreement, are some of the starkest yet from the Tennessean who, despite his at time heated disagreements with Trump, still speaks with the president regularly.

The Trump administration has sought to re-negotiate some of the terms of the Iran nuclear agreement in an effort to make the conditions more restrictive on Tehran, including the so-called “sunset” provisions, which allow some of the limitations on Iran’s nuclear program to expire. But Corker’s comments indicate that those negotiations with European partners are not progressing well.

The senator, who is not seeking re-election this year, said he remained hopeful that negotiations would be successful, especially with French President Emmanuel Macron and German Chancellor Angela Merkel set to visit the White House in the coming weeks. But he ultimately concluded that Trump is “perfectly fine walking away from” the deal.

“But, again, it’s his decision. Executive decisions change when there’s a new executive,” Corker said, mentioning Trump’s decision to withdraw from the Paris climate accord. “Executive agreements just do not stand the test of time. But I hope we reach a framework agreement.”

Congress had been considering passing legislation to scrap the provisions requiring Trump to certify every few months whether Iran was complying with the terms of the deal. Corker, who worked closely with ousted national security adviser H.R. McMaster and fired Secretary of State Rex Tillerson on the effort, was hopeful that it could allow the U.S. to quietly remain in the deal without requiring Trump to publicly approve an accord that he called the worst-negotiated deal in presidential history.

But lawmakers, led by Corker, instead told the administration to come up with a framework agreement with the European partners before coming to Congress. Democrats weren’t likely to sign onto such legislation unless the Europeans were comfortable with a new framework that addresses the Trump administration’s concerns, Corker said.