Trump is clearly butt hurt over Taylor's endorsement of Kamala Harris, because he posted in ALL CAPS Sunday on Truth Social, “I HATE TAYLOR SWIFT!”

Trump is true to form here ... support him -- like Laura Loomer -- he's your best friend. But if you cross him, well, God help you.

Taylor is proving to be problematic for Trump's campaign ... in the first 24 hours after she endorsed Harris, more than 400,000 people registered to vote. That's a HUUUGE number, since the last election was decided by only 44,000 votes in Georgia, Arizona and Wisconsin. And people continue to take Taylor's advice and register.

Trump's hatred toward Taylor is a turn, though eminently predictable. He once said, "I think she’s beautiful, very beautiful! I find her very beautiful. I think she’s liberal. She probably doesn’t like Trump. I hear she’s very talented.”

Well, Taylor knew what she was getting into ... so no surprises here.