Most political observers had assumed that former Montana Gov. Brian Schweitzer would seek the Senate seat being vacated by Max Baucus, who is retiring. Had Schweitzer decided to run, the seat would probably lean toward a Democratic hold, and the GOP would have only an outside chance at taking back the upper chamber.
But Schweitzer's surprise announcement that he will not run changes that calculus substantially. Republicans aren’t favored to win back the Senate, but suddenly there is a pretty clear path forward.
The path begins with Republicans holding their all of their own seats. This will probably be the case, barring a surprise retirement by Maine’s Susan Collins. There is some potential for a Democratic upset in Georgia, particularly if Republicans were to nominate someone likely to implode. But Georgia is still a pretty conservative state with a badly polarized electorate, and Democrats don’t yet have a top-tier candidate.
The other potential Democratic pickup is in Kentucky. I’m actually more bullish on Alison Lundergan Grimes’ chances of defeating Mitch McConnell than are most other analysts on either the left or right. But I still view it as a race that leans GOP.
So as we turn to the Democratic seats in play, our baseline is 45 Republican senators (assuming that a Democrat wins the special election for Frank Lautenberg’s New Jersey seat). Most analysts think that Republicans are in the pole position to pick up the seat of retiring Democrat Tim Johnson in South Dakota, which would give the Mount Rushmore State its first all-Republican delegation since 1962. In West Virginia, Democrats are still struggling to recruit a top-flight challenger against the likely GOP nominee, Rep. Shelley Moore Capito, to fill the seat of retiring Jay Rockefeller.