Brian Schweitzer just didn’t want to be senator.

When the former Montana governor announced Saturday that he was not going to run for U.S. Senate in 2014, it dramatically altered the national political landscape. Schweitzer, a Democrat, would have been heavily favored to win in a state that otherwise leans Republican in federal races. In fact, according to Nate Silver of The New York Times’s 538 blog, Schweitzer’s decision not to run has made it significantly more likely that Republicans will be able to gain a majority in the Senate.

The question that political insiders are asking though is why Schweitzer would pass up a Senate race in which he was considered a heavy favorite. Some are pointing to stories about Schweitzer’s links to “dark money” that started appearing last week. As Bowen Greenwood, executive director of the Montana Republican Party told the Daily Beast, Republicans were “making a healthy effort [to gather] opposition research … worked hard distributing it to local media.” The dark money may have only been the tip of the iceberg. In fact, one source familiar with the race went so far as to tell The Daily Beast that Democrats were likely “better off with an underdog than a candidate likely to implode.”

Montana Democrats though indicated that these stories had nothing to do with Schweitzer’s decision. Instead, they suggest he simply didn’t want to be a senator; let alone live in Washington, D.C. As Schweitzer said in a June interview with Roll Call, “And I concluded it was really bad to live [Washington, D.C.]—traffic is bad, weather is worse. Most of the people you talk to are frauds.”

Schweitzer’s decision leaves an unsettled field. Although there are a number of GOP candidates already, one Republican insider said that if Congressman Steve Daines decides to run, he would likely clear the field. On the Democratic side, the most-talked-about candidate is Stephanie Schriock, the head of Emily’s List. Schriock is a Montana native who managed Jon Tester’s 2006 Senate campaign and then served as his chief of staff before going on to run Al Franken’s 2008 campaign for the Senate. While Schriock would likely be a formidable fundraiser with her ties to the Democratic establishment in Washington, she would be handicapped by the fact that she hasn’t lived in Montana for years, not to mention that being a loyal Salon reader usually isn't the recipe for electoral success in the Mountain West.