Tonight’s first televised debate in the Bay State’s U.S. Senate race may be between U.S. Sen. Scott Brown and Elizabeth Warren — but GOP presidential nominee Mitt Romney could be the one who steals the show, according to pundits and party operatives.

“Mitt Romney is going to be looming large,” said Alan Schroeder, a Northeastern University political science professor who specializes in debates. “Warren has a great opening here. One of the things in any debate that you want to do is go on offense and make the person defend his territory.”