(CNN) President Donald Trump slammed Arizona Republican Sen. Jeff Flake on Twitter on Sunday evening, calling his political career "toast" after he was caught on mic criticizing the President and Alabama Republican Senate candidate Roy Moore at an event on Friday.

Flake was hosting a town hall event at aerospace company GECO in Mesa, Arizona, and was fielding questions about the Republican tax reform plan and a possible 2020 run against Trump when the incident occurred.

After an hour of discussion, Flake stepped off the stage without removing the microphone on his lapel, which was still feeding to the TV cameras in the back of the room.

While speaking to Mesa Mayor John Giles, Flake said if the GOP becomes "the party of Roy Moore and Donald Trump, we are toast."

Trump hit back Sunday using the senator's own words, tweeting, "Sen. Jeff Flake(y)" will "be a NO on tax cuts because his political career anyway is 'toast.'"

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