Jon Tester
Mason-Dixon for the Billings Gazette (3/14-16, registered voters, no trendlines):
Jon Tester (D-inc): 46
Denny Rehberg (R): 45
Undecided: 9
(MoE: ±4%)
I have a feeling we're going to keep seeing polls like this for a long time in this race. The handful of surveys we've seen so far have all shown a tight race: PPP had Rehberg up two back in November, while a conservative pollster had the Republican up three more recently. As Crisitunity points out, both men pull equally well from members of their own party; Tester keeps it competitive because of a 49-37 lead among independents. This will probably be our most titanic clash in the fight to hold the Senate this cycle, and it's hard to see us maintaining control of the body without winning this contest.
Mason-Dixon also checked in on job approval ratings for Montana's statewide elected officials. Tester has a 50% approval score, while Rehberg has a similar 48. (Oddly, the Billings Gazette didn't report disapprovals.) Tester's performance is all the more impressive, given Barack Obama's 40% rating. Meanwhile, if you're looking ahead to 2014, Max Baucus might want to consider retirement: His high-profile role in the healthcare fight tanked his numbers, with only 38% approving. Two years ago, he was the most popular pol in the state, at 57%. That title is now held by outgoing Gov. Brian Schweitzer, who can't run again due to term limits. Schweitzer sports an impressive 60% approval rating, and could conceivably challenge Baucus in a primary next cycle. That, too, would be a pretty epic battle.