By Larry Kane
PHILADELPHIA (CBS) – As voters head to the polls in Michigan, today, there are two mainly overlooked factors that could make this a night of upheaval.
Factor one: Michigan has open primaries. Democrats and Independents can vote in the Republican primary between Rick Santorum, Mitt Romney, Newt Gingrich and Ron Paul. That provides an open field for Democrats to help decide the outcome.
Factor two: unlike Pennsylvania and our region, delegates are voted by county. So, Romney could win the popular vote, Santorum could take the most delegates or the other way around. The race is so close right now.
Arizona seems a lock for Romney, but Michigan could be affected by the first national poll showing Rick Santorum ahead of the President.
And, over their shoulders, the candidates are looking at Ohio next week, where Santorum is now ahead by seven points.