According to the United States Constitution every six years there are elections to vote for a new senator. Thus, the Democrat senator of Montana, Jon Tester, would need to wait until 2018 to run again for senator. As a matter of fact, he ran in the 2018 election and he won with a total of 50.3% of the votes (253,876 votes), while his opponent, Matt Rosendale, only got 46.8% of the votes.