Dan Osborn, the Nebraska independent Senate candidate presenting himself as a political moderate in the deep-red state, is getting a late boost to his campaign from liberal megadonors, dark money groups, and PACs, campaign finance disclosures reviewed by the Washington Free Beacon show. Osborn, running against Republican incumbent Deb Fischer, is backed by Washington, D.C.-based PAC Retire Career Politicians, which has spent hundreds of thousands of dollars on ads that urge Nebraskans to "vote