Surprise! Alec Baldwin will reprise his Donald Trump impersonation on the Sept. 30 season opener of “Saturday Night Live,” he tells Ellen DeGeneres in a pretaped interview for the Wednesday edition of “Ellen.”

In the interview — to promote “You Can’t Spell America Without Me,” his sendup of the Trump presidency’s first 100 days, co-authored with Kurt Andersen — he was asked about the return.

Said Baldwin: “The season premiere is Sept. 30 and I’m gonna do that. I’m gonna do a couple of them. We’re going to do it until...”

(Cue to an exaggerated comic facial twinge, where he mock-wonders whether he should tell a national audience what he really thinks about this impersonation business and this president, and whether “until hell freezes over or impeachment” sounds a little too extreme, he says.)

“Well, nevermind.”

Baldwin pronouncements on his Trump impression have now become news — ephemeral news, but news nonetheless. It’s testament to the star power of both the mocker and the mocked. When he spreads those hands and squints those eyes, viewers know what’s coming — and they can’t get enough. “SNL”’s season 42 had its best viewing levels in nearly a decade, in large measure due to someone who’s not even a cast member.

Baldwin had earlier told CNN that he would be back on “SNL” this season, but his arrival on the premiere is logical. To further parse that ellipsis — in which he hesitates to say how much longer he’ll do this — here’s a reasonable guess: for at least the next three years.

Whether you love his Trump or are cool to his Trump, Baldwin/Trump is going nowhere. He can’t.