(AP) -- The race for governor between Republican Nikki Haley and Democrat Vincent Sheheen, as well as several key congressional races highlight the midterm election in South Carolina.

The campaigns by Haley and Sheheen to replace Gov. Mark Sanford are the most expensive in state history.

Polls opened at 7 a.m. and were scheduled to close at 7 p.m.

There's only a 10 percent chance of rain statewide.

About 130,000 absentee ballots - a record for midterm elections - were cast before Election Day. But election officials are unsure whether that means more voter interest this year or just that people are more comfortable voting absentee.

One of the most heated key congressional races is in the 5th District between Democrat John Spratt, the House Budget Committee chairman, and Republican Mick Mulvaney.

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