If I'd applied my Most Valuable Democrat methodology to the Senate rather than the House, Byron Dorgan would have been a pretty good candidate for the #1 position. Although he's not quite a rank-and-file liberal, he's more progressive than his colleague in the Senate, Kent Conrad, and way more progressive than you'd ordinarily expect of a Senator from a Prairie State, Democrat or otherwise. But today, he announced his intention to retire.
This is un-spinnably bad news for the Democrats, and North Dakota advances to the #1 position in our Senate race rankings. Perhaps this means that John Hoeven was going to challenge Dorgan for the Senate seat anyway and perhaps it doesn't. But in either case, Hoeven's entry into the Senate race would now seem likely and Democratic hopes are probably contingent upon Hoeven not running and Earl Pomeroy, North Dakota's at-large representative, so doing, a rather dicey parlay in what will likely be a bad national environment for the Democrats.