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 a 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. Season 42 of “SNL” had its best viewing levels in nearly a decade, in large measure due to someone who’s not even a cast member.

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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.