And then he went to work for him.
Pompeo, an Army veteran, would go on to serve as CIA director under Trump before becoming secretary of state. He's now one of Trump's most loyal and trusted advisers, despite his past criticism of the commander-in-chief. Pompeo has reportedly been considering a Senate run in Kansas.
But the secretary of state is hardly the only senior member of Trump's administration who's been critical of the president in the past.
White House counselor Kellyanne Conway, for example, spent much of the 2016 presidential primary season attacking Trump on cable news and describing him as "unpresidential" and someone who uses "vulgar" language that's "unfortunate for children."
The president has turned a number of former critics into key allies, including lawmakers like GOP Sen. Lindsey Graham of South Carolina, who in 2015 referred to then-candidate Trump as a "race-baiting, xenophobic religious bigot." Today, Conway and Graham, much like Pompeo, are among the first to stand-by Trump when he sparks controversy with his rhetoric or policies.
From Pompeo warned Trump would be an 'authoritarian president' in 2016. Now he's one of Trump's most loyal and trusted advisors