(Bloomberg) -- Warren Buffett stayed out of the political fray in his annual letter to investors.

The billionaire didn’t mention the words “election,” “Trump,” or any Democrat running for president in the letter released Saturday.

Buffett has trod carefully over the years as the U.S. has become more politically polarized. His annual letter in 2019 focused on overall prosperity in the U.S., saying that America’s success over the decades has been achieved in a bipartisan manner.

Buffett’s been known to campaign for candidates, including Democrat Hillary Clinton in the 2016 presidential election. He’s said more recently, though, that he prefers not to use his position at Berkshire to promote his political views -- or, conversely, to impose his political opinions on Berkshire’s business activities.

That’s meant that he’s avoided having Berkshire take a position on contentious topics such as gun control, even as Bank of America Corp. -- which counts Berkshire as its largest investor -- said almost two years ago that it would stop lending to companies that make assault-style guns used for non-military purposes.

Buffett wrote in 2013 that although he voted for Barack Obama the previous November, 10 of the 12 daily newspapers that Berkshire owned at the time endorsed the Republican candidate, Mitt Romney.

In the 2015 letter, written during the 2016 election campaign, Buffett said candidates “can’t stop speaking about our country’s problems” but that their downbeat views on the U.S. were “dead wrong.”

The son of a four-term Republican U.S. Representative has voted for more Democrats than Republicans over the the past 30 years, he said last year.

He attended fundraisers for both Clinton and Obama ahead of the 2008 Democratic primaries.

While he’s yet to publicly endorse for November’s election, Buffett said in early 2019, ahead of any campaign announcement, that he would support Michael Bloomberg if he ran for president.

(Bloomberg is the founder and majority owner of Bloomberg LP, the parent company of Bloomberg News.)

To contact the reporter on this story: Katherine Chiglinsky in New York at kchiglinsky@bloomberg.net

To contact the editors responsible for this story: Michael J. Moore at mmoore55@bloomberg.net, Ros Krasny, Matthew G. Miller

©2020 Bloomberg L.P.