Bob Corker, R-Tenn., in a Sunday morning Twitter tirade, alleging that the Tennessee Republican "begged" him for an endorsement, did not receive it and "didn't have the guts" to run for re-election.
The Republican senator, who announced his retirement last month, also praised Chief of Staff John Kelly, Secretary of State Rex Tillerson and Secretary of Defense James Mattis as the "people that help separate our country from chaos" by refusing to admit that he was referring to President Trump as the "chaos" he mentioned.
In addition, Mr. Corker, who leads the Senate Foreign Relations Committee, could play a key role if Mr. Trump follows through on his threat to "decertify" the Iran nuclear deal, kicking to Congress the issue of whether to restore sanctions on Tehran and effectively scuttle the pact.
The president then went on to say that the senator was "largely responsible" for the Iran nuclear agreement before concluding that Corker was always going to be a "negative voice" against the Trump administration. "Didn't have the guts to run!"
Senator Bob Corker addressed the comments with his own tweet about an hour later. Corker, in his turn, commented on Trump's tweets by saying that the "White House has become an adult day care center". "Someone obviously missed their shift this morning", Corker tweeted on Sunday.
But The Associated Press has reported that Trump and Corker met privately at the White House last month, and Trump urged Corker to run.
Corker was considered for both vice-president and secretary of state and was a key Trump ally during much of the 2016 campaign.
Corker also said Tillerson has not received the support he needs from Trump.
Corker, a two-term lawmaker isn't seeking re-election. Corker also made it known he's not totally sold on the GOP's tax cut plan this past week, so it was only a matter of time before Trump publicly tried to insult him.