Republican incumbent: Mitch McConnell
Democratic candidate: Bruce Lunsford
McConnell, 66, has been in the Senate since 1985, and has been the Senate Republican leader since 2007.
Lunsford, 60, is a lawyer and businessman. He has been appointed to various positions in state government. He ran unsuccessfully for governor in 2003 and 2007.
Polls cited in Real Clear Politics show McConnell ahead by margins ranging from 10% to 12%.
Kentucky is a classic "border state" in the sense of being a slave state that stayed in the Union during the Civil War. It was neither as strongly Democratic as states further south, before the 1960s, nor as strongly Republican thereafter.
Republican Jim Bunning has been in the other Senate seat since 1999.
Republicans cannot call this a safe seat, but Lunsford faces an uphill battle to unseat McConnell. One wild-card element is that Lunsford has a substantial personal fortune to help bankroll his campaign.