Tuesday, voters cast their ballots for the nominees for president and the delegates that will head to the Republican National Convention in Tampa this summer.
In the republican presidential race, there are 54 delegates at stake.
"This area's kind of a mixed bag," said Susan Carpentier, Chairman of Rock Island County Republicans. "So, I'm not sure how that's going to turn out. It's going to be pretty exciting."
Romney is considered the frontrunner, largely due to support among moderates in places like Chicago.
Santorum is expected to show well among conservative voters in the southern part of the state.
"Gov. Romney's had boots on the ground for a year and does have a slate of votes in each congressional district, where Santorum does not have delegates to vote for in every congressional district," said Carpentier.
One way pollsters try to predict who'll win an election is by conducting an exit poll.
Besides asking voters which candidate they voted for- "They'll stop a voter as they're leaving the polls and ask what issues are important to them," she said.
Campaigns then use that information to determine how to go forward in a race.
"If they are hearing in their exit polling that the majority of people voting today are concerned about the economy, then their message better start being about that."
But, how indicative the exit poll results are of an actual win is sometimes hard to gauge.
"The last time President Bush ran in Ohio, his exit polls were in the dark and everyone seemed so concerned and he actually ended up carrying Ohio."
What we do know from the exit polls, is that voter turnout in Illinois has been extremely low.
Susan says she had hoped it'd be better considering that it's been decades since Illinois had a significant hand in nominating a presidential candidate.