Aren't Nebraska, Kansas, and Oklahoma pretty similar politically? OK, I realize that Kansas and Oklahoma have Democratic governors and a few Democratic representatives to Congress, but other than that, I'm not sure what the big difference might be. Is one of these states clearly much less conservative than the other two?
What would cause a Democratic nominee to do that much better in one of these states than the others? If Kathleen Sebelius were on the ticket, Kansas would be most likely to go Democratic. If Brad Henry were on the ticket, Oklahoma would be most likely to go Democratic. If Ben Nelson or Bob Kerrey were on the ticket, Nebraska would be most likely to go Democratic.
Kansas is more socially moderate than Oklahoma. That is why I would pick Kansas before Oklahoma.