Dan Osborn at his home in Omaha, Nebraska, last week. Photo: KC McGinnis/The New York Times/Redux The return of Nebraska Senate candidate Dan Osborn is the best news Democrats have received in a while. The irony, of course, is that Osborn is not running as a Democrat at all. He’s launching a second independent bid, this time against Republican Pete Ricketts. Osborn gets relatively little national attention — a recent New York Times column was the exception , not the rule — and he never parlayed