It's Warren Buffett season.

The billionaire and CEO and chair of Berkshire Hathaway, Inc. sent his annual shareholder letter out this weekend, and appeared Monday on CNBC's Squawk Box, where he weighed in on various topics, including the 2020 presidential election.

Buffett normally supports Democratic candidates, but he admitted he's not a "card-carrying" member of the party and has contributed to and voted for Republicans in the past. There was no indication he'd support President Trump's re-election in the interview, but he did seem hesitant about supporting Sen. Bernie Sanders (I-Vt.) if he winds up as the Democratic nominee. Buffett didn't denounce Sanders — in fact, he said he agrees with him on some counts, especially the argument that "we ought to do better by the people who get left behind by our capitalist system" — but he said he'll wait to see what happens before making any sort of declaration.

One Democratic candidate he doesn't seem concerned about voting for is his fellow billionaire, former New York City Mayor Michael Bloomberg. Buffett said he'd "certainly" vote for Bloomberg, but his own self-awareness seems likely to prevent him from endorsing him during the primaries. "I don't think another billionaire supporting him would be the best thing to announce," he said. "But sure, I would have no trouble voting for Mike Bloomberg." Read more at CNBC. Tim O'Donnell