Sen. Jeff Flake was caught on a hot mic Friday bashing President Donald Trump and Alabama Senate candidate Roy Moore.

Flake’s gaffe occurred at a tax reform event in Mesa, Ariz., ABC News reports. The Arizona senator was talking to friend and Mesa Mayor John Giles, and apparently did not realize his microphone was still on. “If [Republicans] become the party of Roy Moore and Donald Trump, we are toast,” ABC affiliate KNXV caught Flake saying.

Flake’s comments on Friday may not have been intended for public consumption, but the Republican has made himself a highly visible Trump adversary in the past. Most notably, Flake announced in October that he would conclude his Senate service in January 2019 due to the state of the administration and the political climate.

“I am aware that a segment of my party believes that anything short of complete and unquestioning loyalty to a president who belongs to my party is unacceptable and suspect,” he said on the Senate floor. “If I have been critical, it not because I relish criticizing the behavior of the president of the United States. If I have been critical, it is because I believe that it is my obligation to do so, as a matter of duty and conscience.”

Giles, meanwhile, was caught making some inflammatory comments of his own on Friday, while apparently encouraging Flake to run for president, ABC reports.

“Think about how much fun it would be — just to be the foil, you know, and point out what an idiot this guy is,” Giles said, seemingly alluding to Trump. “Anyway, I hope you do it.”

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Write to Jamie Ducharme at jamie.ducharme@time.com.