In blow to Democrats, Schweitzer won't run for Senate

NBC News has confirmed that former Montana Gov. Brian Schweitzer (D) won't run for next year's vacant Senate seat, which is a blow to Democrats. 

It was widely assumed that a Schweitzer candidacy would help the party hold onto the seat vacated by retiring Sen. Max Baucus (D). 

Democrats are now pointing to at least three possible candidates to run in 2014:

-- Stephanie Schriock, president of EMILY's List

-- state Schools Superintendent Denise Juneau

-- Insurance Commissioner Monica Lindeen 

Republicans need to pick up six Senate seats to take control of the chamber in the 2014 midterms. 

The GOP is already favored in West Virginia and South Dakota. And with Montana definitely on the board, that means that Republicans need to win four out of these six competitive races: Alaska, Arkansas, Iowa, Louisiana, Montana, and North Carolina. 

That's a doable -- though very narrow -- path.