Former Sen. Jeff FlakeJeffrey (Jeff) Lane FlakeMcSally ties Democratic rival Kelly to Sanders in new ad McSally launches 2020 campaign Sinema will vote to convict Trump MORE (R-Ariz.) responded to President TrumpDonald John TrumpChasten Buttigieg: 'I've been dealing with the likes of Rush Limbaugh my entire life' Lawmakers paint different pictures of Trump's 'opportunity zone' program We must not turn our heads from the effects of traumatic brain injuries MORE’s remarks that he is "very happy" some Republican senators have left and "gone on to greener pastures."

Flake, a frequent Trump critic before leaving the Senate last year, responded by tweeting a picture of himself standing on a beach with the caption "greener pastures."

Flake included a link in the tweet to a report detailing the remarks Trump made Wednesday while speaking to the Faith and Freedom Coalition.

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Flake shot down rumors of a possible 2020 challenge to Trump and joined CBS News as a political contributor. He is set to join Harvard's Institute of Politics this fall as a resident fellow.

Although he was a vocal critic of Trump and many of his hard-line immigration policies, Flake voted with the Republican bloc most of the time.

It is unclear who Trump was referring to with his "greener pastures" remarks Wednesday, but he had previously referenced the late Sen. John McCainJohn Sidney McCainMeghan McCain after Gaetz says Trump should pardon Roger Stone: 'Oh come on' Advice for fellow Democrats: Don't count out Biden, don't fear a brokered convention McSally ties Democratic rival Kelly to Sanders in new ad MORE (R-Ariz.) in the speech, leading many to think the comment was about him.