Presumptive Republican vice presidential nominee Paul Ryan was heckled Monday by protesters at a campaign event in Iowa. Time senior political analyst Mark Halperin told MSNBC's Chris Matthews these were Democrats "on duty" (video follows with transcript and commentary, photo courtesy Des Moines Register): Mark Halperin: Ryan Protesters In Iowa Were Democrats 'On Duty' CHRIS MATTHEWS, HOST: Anyway, Paul Ryan was met by a loud group of protesters today who joined his supporters at the same state fair event in Iowa. They booed and yelled throughout his ten minutes, but he handled it pretty well. Let's watch. (BEGIN VIDEO CLIP)...