JB was in San Francisco Wednesday night for the Asia-Pacific Economic Cooperation Conference, which is being hosted by Cali ... and featuring the guest of honor in Chinese President Xi Jinping, who's in town to talk about his country's relationship with the U.S., etc.

While Joe was onstage ... he explicitly shouted out the Gov. with some flattering words -- and based on what he said, a lot of people think he sees him as a would-be successor.

Check it out ... 46 says Newsom's been doing a helluva job for the Golden State, and then added -- "Matter of fact, he can be anything he wants. He can have the job I'm looking for."

Of course, what Biden seems to be referring to here is the presidency itself ... for which he's currently running as he seeks reelection. Joe hasn't signaled he's bowing out for 2024 -- so, presumably, what he means here is that Newsom is primed to run in the near future.

We know Gov. Newsom's ambitious and there's been tons of rumblings in the Democratic Party that he has presidential aspirations -- so Joe confirming that is pretty telling.

BTW, this little get-together they were at yesterday ended up being high-level entertainment ... 'cause Gwen Stefani stopped by to serenade the crowd -- belting out a couple songs and even giving the Prez a hug in front of everyone.