Republican primary voters: Michigan holds open primaries -- meaning you can vote in whichever one you like -- and the AP reports that, although the Democratic primary is essentially meaningless this year, Democratic participation in the Republican primary is low. About two-thirds of the Republican primary voters are Republicans; about a quarter are independents and about 10 percent are Democrats. The combined non-Republican vote appears to be just few ticks smaller than Politico's Jonathan Martin says it was in 2000, when John McCain won the primary.
Democratic primary voters: Not surprisingly, turnout for the Democratic primary seems to be extremely low. The AP says about 70 percent of the voters it's finding are voting in the Republican primary.
The Clinton referendum: Hillary Clinton is the only major Democratic candidate on the ballot. We don't have a sense yet of how many voters will vote "uncommitted" instead of casting votes for her, but the AP says that "younger voters, college graduates, blacks and voters in bigger cities were more likely than other groups" to do so.
The issues: In a state with the highest unemployment rate in the nation, nearly half of the Republican voters surveyed said the economy was their No. 1 issue. Only about 20 percent put Iraq at the top of their list, with immigration the top choice of even fewer GOP voters.