From a Washington Post story by Nick Tabor headlined “Sean O’Brien’s summer of the strike”:

As 8 a.m. brought the end of the night shift at a suburban UPS distribution center, Sean O’Brien stood in the parking lot and sized up two of the men walking out.

Black shorts, black T-shirts, black sneakers. These guys weren’t drivers; they worked inside the warehouse.

A local union official with a graying handlebar mustache beckoned the two men. “How’s it going, guys? Meet Sean O’Brien — general president of the Teamsters union. Come on over! Say hi.”