King told CNBC's "Squawk Box" he's known Trump for 45 or 50 years. "I had him on [TV] countless times. I've dined with him. I've socialized with him," said King, who spent a quarter century hosting "Larry King Live" on CNN and now hosts two programs on Hulu.
"It's a very tough pick because I've known Hillary a long time, too. And I'm friends with both. I socialize with both, and like them both," King said. "Some of [Trump's] stands, I just can't go with."
"When I'm down to the two, I would tell Donald, 'Donald, I love you. You're a great friend. But I can't buy some of the things [you've said],'" King said, making a reference to Trump's accusations of bias against the Mexican-American judge in the Trump University case.
Before pulling back on comments under pressure from Republicans, including House Speaker Paul Ryan, Trump had been saying the judge could not be impartial because of his heritage, given the candidate's call to build a wall along the U.S.-Mexico border.
King said he tends to vote Democratic. "But I'm very independent." He recalled he voted for Richard Nixon in the 1968 presidential race, which saw the California Republican win his first term in office. "I could always be swayed."
"[But] The Donald I know was pro-choice ... [and] anti-guns," King said. Trump has been campaigning on the traditional Republican platform of supporting anti-abortion views and the sanctity of the right-bear-arms Second Amendment.
Disclosure: Comcast, which owns CNBC parent NBCUniversal, is a co-owner of Hulu.