There's a big Senate primary runoff in Georgia on Tuesday night, with Rep. Jack Kingston facing off against businessman David Perdue in the GOP race to face Democrat Michelle Nunn.
The winner of Kingston/Perdue will be a favorite in November, but he will have to defend a state that Democrats say they will vigorously target.
For those following the results tonight (results here), we figured we'd give you a little tool to help you along the way.
Below, are the county-by-county results from the primary two months ago, in which Perdue finished ahead of Kingston, 31 percent to 26 percent.
Given Perdue's margin in the last race, we have created a baseline (on the right) that he will want to beat in any given county. If Perdue is beating that baseline in lots of counties and/or in the most populous ones, he's probably on track to win; if he's not, Kingston probably comes out on top.
This is not a perfect method -- especially given that each man has particular regional strengths and there are so many voters up for grabs. Perdue, for instance, might expand his margins in the populous Atlanta counties -- where he did well last time -- while Kingston could expand his margins downstate, where his congressional district is.
But as the night progresses, keep an eye on how the two candidates are running across the state compared to last time, and you'll have a pretty good idea about in which direction things could be headed.