Across the country, early voting for Tuesday's midterm election has been happening in record numbers – where it’s available – in state after state: Maryland, North Carolina, Georgia, Texas. More than 28 million Americans have already cast their votes to date. Here in California, the numbers aren’t quite as impressive. By the middle of this week, about 2.5 million ballots had been returned by mail, which is about average. So, what is likely to happen on Tuesday when polls open? Who can be counted on to show up?