Student or Learner
Does it mean "Democrats need to show up to whom (the few thousand union members)"?
“They’re betting that between now and November, you’re going to come down with amnesia,” the president said of the GOP. Wearing neither a jacket nor a tie, and with shirt sleeves rolled up, a feisty Obama sought to rev up a few thousand union members — the very voters he won two years ago, and whom Democrats need to show up at the polls in November to mitigate GOP gains.
Democrats need them to show up and vote.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.