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 FischerDebra (Deb) Strobel FischerDefense bill moves forward with lawmakers thinking about McCain Pruitt’s renewable fuel attacks cost him GOP support in Congress Meet the Democratic sleeper candidate gunning for Senate in Nebraska MORE win the primary last month. 

The Hill rates the race as "likely Republican."