President Trump went after Sen. Jeff Flake (R-AZ) in a Twitter post Thursday morning. Flake, a harsh critic of President Trump, announced last fall that he will not see re-election and will retire when his senate term ends.

Trump tweeted:

How could Jeff Flake, who is setting record low polling numbers in Arizona and was therefore humiliatingly forced out of his own Senate seat without even a fight (and who doesn’t have a clue), think about running for office, even a lower one, again? Let’s face it, he’s a Flake!

Flake tweeted on Wednesday that he plans to speak on the Senate floor Thursday morning.

“I plan to speak on the Senate floor tomorrow morning to discuss the administration’s protectionist policies and the importance of America’s leadership in the world,” Flake stated.