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Story highlights

Vice President Joe Biden appeared on "The Late Show" with Stephen Colbert on Tuesday night

The Vice President joked about his age, saying he'd "still be in better shape" than Trump, who is 3 years younger, in 2020

(CNN) —  

Vice President Joe Biden continued to tease a presidential bid in 2020 during an appearance on “The Late Show” with Stephen Colbert on Tuesday night, saying he’s learned to “never say never.”

“I’m a great respecter of fate. I don’t plan on running again. But to say you know what’s going to happen in four years, I just think is – is not rational,” Biden said.

After stoking speculation about his 2020 ambitions with comments to reporters earlier this week, Biden sat down for an interview with the late night host and discussed another potential run and the incoming Trump administration.

The Vice President – who would be 77 years old in 2020, which would make him the oldest upon entering office – jokingly dismissed concerns about his age, quipping that he’d still be “in better shape” by the next election than President-elect Donald Trump.

“I can’t see the circumstance in which I’d run, but what I’ve learned a long, long, long time ago, Stephen, is to never say never. You don’t know what’s going to happen. Hell, Donald Trump is going to be 74. I’ll be 77 and in better shape. Who knows?” Biden said to laughs.

Concerning the new administration, Biden said “the honest to god truth is I don’t know” what to expect.

“Y’all are going to laugh when I say this,” he said. “But I’m being deadly earnest here. I don’t think – I don’t think the president himself knows for certain.”

But Biden struck cautious tone, praising some of Trump’s cabinet appointments as “very solid” while warning that other picks suggest a “harmful” and “dangerous” direction.

“If you look at the people that Donald Trump has named so far, some give me great pause. There’s other people he’s appointed in the administration that are very solid. Elaine Chao is fully capable of being a great secretary of labor. So it’s just – I don’t think anybody knows for certain, but we have to be vigilant, and when in fact it looks like the administration is moving in the direction that is harmful or dangerous.”

CNN’s Kevin Liptak contributed to this report.