On Tuesday, Flake gave a speech on the Senate floor to announce he wouldn’t seek re-election. He also made headlines for using the platform to slam President Donald Trump and those who support him.

“Mr. President, I will not be complicit or silent,” Flake said.

“No, I will be complicit and absent,” the CBS “Late Show” host fired back after the clip.

Colbert then laid into Flake and other Republicans who only call out Trump after they decide to leave office.

“Why is it that Republicans only speak up against Donald Trump when they know they’re not running for reelection?” Colbert said. “They finally grow a set. Then they say, ‘I’m taking my balls and going home.’”

See his full monologue above.

Colbert’s cracks about Flake begins at 6:10.