It wasn’t too long ago that most of Washington was expecting that the Republicans would add to their House takeover in 2010 by taking control of the Senate next year, no matter who was elected president. Just a year ago, the experts had the Senate divided 54-46 in favor of Republicans after this fall’s election, with some giving the Republicans a fillibuster-proof 60 seats.

But Democratic successes in picking candidates and fundraising, coupled with bitter GOP primary fights, has analysts now expecting a chamber split 50-50, with a possibility that the Republicans get 51.