Berkshire Hathaway CEO and Omaha native Buffett emerged as a political player last year when President Obama named a proposed rule to raise tax rates on the wealthy after him. He has campaigned for Obama, but typically is known for shying away from public events.

Kerrey, a former Nebraska governor, in a tough race with opposition from well funded Republican groups and grassroots activists who helped Sarah Palin-backed Republican candidate Deb FischerDeb FischerLobbying World Congress must stop the assault on taxpayer-friendly freight railroads Senate panel won’t vote on bill to boost ethanol MORE win the primary last month. 

The Hill rates the race as "likely Republican."