Today could be a make or break day for several presidential candidates.
In a recent Ohio poll, Hillary Clinton is leading Senator Bernie Sanders by only five percentage points.
Sanders is looking to repeat what he pulled off in Michigan last week. He was trailing Clinton by 20 points going into the wolverine state's primary.
Today could be Governor John Kasich's last stand as well.
The governor is saying if he does not win Ohio, it will be time to "call it over."