Tennessee Republican Sen. Bob Corker didn’t hold back Sunday in response to President Donald Trump’s attacks over Twitter.

“It’s a shame the White House has become an adult day care center. Someone obviously missed their shift this morning,” Corker tweeted.

Trump tweeted earlier Sunday that Corker, who is not seeking re-election in 2018, “begged” Trump to endorse him.

“I said ‘NO’ and he dropped out,” Trump tweeted. “He also wanted to be Secretary of State, I said ‘NO THNKS.’ He is also largely responsible for the horrendous Iran Deal!” (RELATED: Sen. Corker’s Height, Business Dealings Hurt His Secretary Of State Chances)

“Hence, I would fully expect Corker to be a negative voice and stand in the way of our great agenda. Didn’t have the guts to run!” Trump continued.

Corker, who is the chairman of the Senate Foreign Relations Committee, said in August that Trump “has not yet been able to demonstrate the stability, nor some of the competence that he needs to demonstrate in order to be successful.”

Then this past Wednesday, the senator said that chief of staff John Kelly, Defense Secretary Jim Mattis, and Secretary of State Rex Tillerson are the people “that help separate our country from chaos.”

White House Counselor Kellyanne Conway claimed Thursday that Corker’s comments were positive.

“Well, the chairman and the president have had a good working relationship all along, as you have said, dating back to transition and certainly the campaign. Senator Corker was in the White House a couple weeks ago for a private meeting with the president,” Conway said. “What I think — I took those comments to mean that Senator Corker was talking glowingly, and frankly accurately, about the leadership we have in this White House through General Kelly, who is our chief of staff, and General Mattis and Secretary of State Tillerson. And it’s really a hand-picked cabinet by this president.”

Corker joins a growing list of Republican lawmakers Trump has feuded with including Senate Majority Leader Mitch McConnell, and Arizona Sens. Jeff Flake and John McCain.