CBS News projects that Mitt Romney will win Ohio's key primary contest Tuesday, after a neck-and-neck race with rival Rick Santorum to eke out a victory in the pivotal battleground state.

With 96 percent reporting in Ohio, Romney has 38 percent support to Santorum's 37 percent. Newt Gingrich is in third place with 15 percent and Ron Paul follows with 9 percent.

Mitt Romney has also won primaries in Virginia, Massachusetts and Vermont, as well as the Idaho caucuses. Rick Santorum won primaries in Tennessee and Oklahoma, and in the North Dakota caucuses. In Georgia, Gingrich clinched his first primary victory since South Carolina's January 21 primary contest.