Ahead of Defense Secretary Jim Mattis’ decision to exit the White House, lawmakers pleaded with him to keep his post as a check on President Donald Trump, Sen. Dick Durbin (D-Ill.) said.

During a “Meet the Press” interview Sunday, Durbin revealed to host Chuck Todd that he and his colleagues had tried to talk Mattis out of his resignation.

“I was one of many senators who privately sat down with General Mattis and said: ‘Please stay. Stay as long as you can. We desperately need your mature voice, your patriotism in the room when this president is making life-or-death decisions about national security,’” Durbin said.

But the senator said it was too late, noting that things had “obviously reached a breaking point” for the defense secretary.

While Durbin thanked Mattis for his service, he lamented his departure, appearing concerned for a future without him.

“It breaks my heart that he’s going to step aside,” Durbin said. “We counted on him to be there and to stop this president from his worst impulse.”

Mattis turned in his resignation letter last week, pointing to differences with the commander in chief over his friendliness toward authoritarian regimes and his decision to yank U.S. forces out of Syria. He was set to officially leave the administration at the end of February, but in a tweet on Sunday, Trump made clear he would be pushed out by Jan. 1. Deputy Secretary of Defense Patrick Shanahan has been tapped to step in as acting defense secretary at that time.