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Despite Donald Trump's campaign pledge to "drain the swamp" in Washington, the president-elect hasn't "done enough" to address his own ethics issues and potential business conflicts, Vice President Joe Biden told NBC News' Andrea Mitchell on Thursday.

"I don't think he's done enough and he may sink in the swamp," Biden said, referring to Trump's refusal to release his taxes and other issues concerning his vast business holdings. "If you don't drain it, you sink in it."

See more of Andrea Mitchell's one-on-one interview with Biden on 'NBC Nightly News'

"Are you going to be president or are you going to be a businessman? You don't do both. You ran for the most coveted office in the world," Biden added.

Trump vowed in a new ethics plan outlined on Wednesday that his business interests would not pose a problem — but Biden said his financial deals shouldn't even be brought up now that he's been elected.

Vice President Joe Biden talks with NBC's Andrea Mitchell. NBC News

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"Focus on your job. That's the job," he said.

In the wide-ranging interview, Biden also touched on Trump's differences with the intelligence community, Vladimir Putin, and the vice president's cancer moonshot program.

Related: White House Proposes $1 Billion for Cancer ‘Moonshot’

Biden addressed the controversy around an explosive, unverified report that Russia had compromising information on Trump, and criticized Trump for denigrating U.S. intelligence in public statements, including on Twitter.

In response to a question about whether it had been a mistake for the U.S. intelligence community to include a summary of that report in briefing materials, Biden said officials felt an "obligation to inform not only us but the president-elect that this was out there."

Trump on Wednesday held his first press conference in six months, a testy briefing in which he sparred with reporters over the unverified report. In a tweet early Wednesday, Trump lashed out at the intelligence community, saying of the leak of the report: "Are we living in Nazi Germany?"

Biden told NBC News he hopes Trump will adopt a more favorable view of U.S. intelligence after being sworn in.

"Once he has the mantle of being president, sitting behind that desk every morning, my hope and expectation is that he will become significantly more informed how they work, how they function, how good they are," Biden said.

Biden said he didn't regret not running against Trump because "I just wasn't prepared to do it after I lost my son." But, he added, "Do I regret that my point of view is not going to be reflected in the next administration because we have Mr. Trump? Yeah, I do regret that."

Comparing the end of the Obama era to the final days of high school, when students pass around yearbooks, he joked his yearbook quote to Trump would be: "Lots of luck in your senior year, Mr. Trump."

Biden praised Obama as a "truly, truly decent man," and said, "I admire him. This man has more backbone, more integrity than any president I've ever worked with. And I've worked with eight presidents."

Michelle Obama, Biden added, "is the finest first lady in history."

"The whole world looks at her and she conveys America," he said.

Biden on Sunday is scheduled to make a swansong visit to Ukraine, one of the nations that has expressed anxiety over the incoming presidency following a Trump remark that he wasn't sure whether some European states should have NATO protection from neighboring Russia until they "have fulfilled their obligations to us."