Republican Sen. Steve Daines has defeated Democratic Gov. Steve Bullock in Montana's race for the U.S. Senate, AP projects.Why it matters: It's a major loss for Democrats in their efforts to flip the Senate blue. Polls consistently showed Bullock and Daines as neck-and-neck, with Cook Political Report rating the race as a toss up. The big picture: The race between Daines and Bullock was the most expensive Senate competition in Montana's history, per the Missoula Current. Bullock is a moderate Democrat whose bid for his party's presidential nomination floundered earlier this cycle. The governor was elected in 2012 and reaches his term limit this year. Daines, however, is a steady Republican vote that sides consistently with President Trump. He was first elected to the Senate in 2014.Data: AP; Chart: Naema Ahmed, Andrew Witherspoon, Danielle Alberti/Axios