There are two big Republican presidential primaries today. One of which is in a candidate's home state.

FOX News Radio's Jeff Monosso and Jessica Rosenthal report:

I'm Jeff Monosso in Grand Rapids.

(Romney) "This sure has been fun these last 10 days or so."

Mitt Romney, who started down about 15-points, edges rival Rick Santorum in the polls, but not by much.

Both front runners canvased western Michigan yesterday, attacking each other's records and experience, and talked energy, jobs, and the economy on a last push for support.

(Santorum) "We need leadership that is going to take us on a different path."

Santorum hoping for an upset and some big momentum.

A loss for Romney in his home state, some say could be disastrous.

In Arizona polls have Romney way ahead of his rivals.

Tom Jenney is with Americans for Prosperity in Arizona, an organization with ties to the Tea Party.

(Jenney) "When you talk to Conservatives, and Tea Partiers in general, they are concerned about fiscal issues. I think primarily I'd say thats the number one issue, but if you're in Arizona, immigration policy is huge."

He says while social issues are big, they're not as important.

Santorum had been moving up in the polls in Arizona, but newer surveys taken after last week's debate showed support for him, dropped.

Jessica Rosenthal, FOX News Radio.