beat on

verb2

1. •
   (figurative) To criticize, impugn or shed a bad light on (a group or topic) for political gain.

   • She's unpopular enough that photos of her are used in elections to beat on liberal candidates.
   • You guys are always beating on immigration, but it won't win you this election.
2. •
   (figurative) To talk at length; to go on and on; to rant or expound.

   • She's beating on about poor service.