Voters in 10 states are heading to the polls for Super Tuesday to make their choice in the Republican presidential primary.

Mitt Romney has momentum heading into the big day after winning Washington on Saturday, his fifth state in a row. He's also racked up endorsements from high profile conservatives, including House Majority Leader Eric Cantor.

Rick Santorum hasn't had a win in nearly a month, but still believes he has a fighting chance, particularly in Ohio. The state is one of tonight's most important contests and is likely to be a big battleground come November.