The honeymoon, it seems, is over.

Sen. Scott Brown, whose unexpected victory saw the end of a legacy of liberalism in Massachusetts, is now refusing an invitation from the Tea Party movement -- and Sarah Palin, the very figures who helped Brown score his Senate seat.

Tea Partiers are gathering for a massive rally on Boston Common where Palin is scheduled to speak Wednesday.

Some experts, not surprisingly, are saying Brown has tossed the Tea Party overboard.

“He wants to mainstream himself before the election,” Larry Sabato, a University of Virginia political scientist, told the Boston Herald, which broke the story.

“You’re worried at a rally that there’s a sign, a statement, an incident that’s certifiably cuckoo occurs,” political analyst Lou DiNatale told the paper. “To win re-election, Scott Brown floating to the right is a serious problem.

“And showing up at a Sarah Palin, Tea Party event is not the way to the middle.”

Brown says he can't attend because of his busy Senate schedule -- but that he applauds the "energy and enthusiasm" Palin and the Tea Party protesters bring to his home state.