Yeah, I thought of Kleeg (but had forgotten his name). Has he been in the public eye since losing in 2006? I don’t think he has run for anything else since then, and it will be difficult for a Democrat in NE with no electoral history to beat a statewide officeholder such as Stenberg or Bruning (or even a congressman such as Fortenberry).
Scott Kleeb actually did run for office again. In 2008, he ran for the Senate against former Gov. Mike Johanns. Johanns beat him pretty handily, 58%-40%. Kleeb only won eight counties, all sparsely populated in the middle of the state except for Lincoln-based Lancaster county, where he barely edged out Johanns by a point. Kleeb also ran pretty far behind Obama in the Omaha area.