Usually by the time voters reach Super Tuesday, the party has a clear leading candidate. This year, however, could bring a little GOP shake-up.
There are ten states holding a primary election or caucus on Super Tuesday2012. Former Massachusetts Gov. Mitt Romney is slated to take about four of them, but has faced increasing competition from previous underdog former Pennsylvania Sen. Rick Santorum. Santorum surprised the Romney camp Feb. 7 when he swept three states - Minnesota, Missouri, and Colorado.
While Romney has won the most elections so far, there is still a large number of Republicans he has failed to win over. Some GOP members think he's too liberal to represent the party in Washington.
With some surprise wins for Santorum already this year, tomorrow's Super Tuesday battle could further rattle Mitt Romney's lead.
As we enter one of the most closely watched days in Election 2012, here's what you need to know.
Super Tuesday 2012
Which states are key? There are 437 delegates in the Super Tuesday states, more than double the amount that already voted. Only 422 technically are up for grabs tomorrow, since the rest are superdelegates and unbound to the results. That's still more than one-third of the 1,144 delegates needed to clinch a nomination.
Here's how they break down per Super Tuesday state: