In a district where Scott Brown won, Sean Bielat mounts a serious challenge. 'I don't consider myself a tea party candidate," Sean Bielat tells me over dinner. "I don't know what it means." But an hour later Mr. Bielat, Rep. Barney Frank's Republican challenger, receives a hero's welcome at the Spindle City Tea Party, a gathering of nearly 200 citizen- activists in this economically depressed mill town. As he approaches the stage, they stand, applauding and chanting "Go, Sean, go!" What he tells them is consistent with this reporter's view of the tea party: "I'm starting to think that people...