President Trump said he doesn't know if Defense Secretary Jim Mattis will leave his administration, but did stress that they have a good relationship despite any political leanings.

"I think he's sort of a Democrat, if you wanna know the truth," Trump told CBS News' "60 Minutes" in an interview set to air in full Sunday night. "But Gen. Mattis is a good guy. We get along very well. He may leave. I mean, at some point, everybody leaves. Everybody. People leave. That's Washington."

[Trump: 'I know more' about NATO than Defense Secretary Jim Mattis]

Trump made the comments after dismissing a question regarding his administration's rapid staff turnover. Just last week United Nations Ambassador Nikki Haley announced she would depart by year's end. But the commander in chief said Mattis, who has served presidents of both political persuasions, had not signaled his intention to step down from his post at the Pentagon.

Trump did, however, foreshadow more exits, saying he had "phenomenal" people on "standby" should vacancies open at the top level of his government.

"Yeah, other people will go, sure," he said. "I think I have a great cabinet. There's some people that I'm not happy with. I have some people that I'm not thrilled with. And I have other people that I'm beyond thrilled with."

A Department of Defense spokesman, Col. Rob Manning, downplayed Trump's comment Sunday, saying Mattis was preoccupied with national security issues rather than speculation in relation to his future at the Pentagon.

"Secretary Mattis is laser-focused on doing his job — ensuring the US military remains the most lethal force on the planet," Manning told the Washington Examiner in a statement.