Voters are heading to the polls in four states on Tuesday — Maine, South Carolina, Nevada and North Dakota. But the race that will get an outsized share of attention is a fait accompli. Maine Gov. Janet Mills suspended her Senate primary campaign over a month ago, but her name is still on the ballot — and all eyes will be on the share of voters who choose Mills anyway to register disappointment with Graham Platner, the now scandal-plagued presumptive nominee.