President Donald Trump tweeted that the reason Sen. Bob Corker (R-Tenn.) will not run for re-election in 2018 is because he couldn’t get Trump’s endorsement.

In a series of tweets Sunday morning, the president attacked one of his most vocal Republican critics in the Senate who said in the aftermath of Charlottesville that the president “has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate in order to be successful,” CNN reported.

Eight days later, Trump tweeted that Tennessee was “not happy” with Corker and claimed that Corker was “constantly asking” him whether to run again. One month after Trump’s initial tweet attacking Corker, the Tennessee Republican announced that he would not seek re-election to the U.S. Senate next year.

On Sunday, Trump took to Twitter, claiming to know why Corker decided against another term.

“Senator Bob Corker ‘begged’ me to endorse him for re-election in Tennessee. I said ‘NO’ and he dropped out (said he could not win without my endorsement). He also wanted to be Secretary of State, I said ‘NO THANKS,'” Trump tweeted.

Trump further said that Corker is “largely responsible for the horrendous Iran Deal!”

“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 added.