CBS late-night host Stephen Colbert unloaded on White House press secretary Sarah Huckabee Sanders on Tuesday over reports that Sanders attempted to avoid Monday's White House press briefing over questions about immigration.

Sanders has denied the reports.

In his monologue, Colbert referred to Monday's White House press briefing, which was delayed for hours while the administration waited for Department of Homeland Security Secretary Kirstjen NielsenKirstjen Michele NielsenTrump confirms Rick Perry to step down as Energy secretary Trump says acting Homeland Security chief McAleenan will step down Activists to demonstrate at ICE headquarters after Cameroonian immigrant dies in custody MORE to fly back to Washington to answer questions on the Trump administration's "zero tolerance" policy that has resulted in separating minors from their guardians at the border.

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“Hucka-Sands didn’t want to do the briefing amid questions about Trump’s child separation policy," Colbert said.

"Sarah, you think you don’t want to talk about child separation policy? Try doing it on a comedy show! ‘Oh, you must love the Trump administration, Stephen — the sadness just writes itself!’ " Colbert joked.

Sanders has said it isn't true that she avoided the press briefing, rebuking CNN over a tweet sent by one of its media reporters.

"Jeff, I'll take your question since you and your network falsely accused me of not wanting to be here, so I will be glad to pass that question on to you now," Sanders told CNN's Jeff Zeleny during the briefing.

During his remarks, Colbert ignored Sanders's denial and stated that, unlike the thousands of children currently held in migrant detainment facilities, Sanders could simply leave the White House if she doesn't want to defend the policy.

“If kids in cages is too much for you to defend, there is one option: You could resign!" Colbert said, to laughs and applause. "This is the White House, not an abandoned Walmart. You’re allowed to leave.”

Thousands of children, some as young as toddlers, are being held in detainment facilities under the administration's zero tolerance policy, which requires that all immigrants without legal status who are apprehended near the border be prosecuted for illegal entry. Several GOP lawmakers and scores of Democrats have denounced the policy as child abuse.