BILLINGS, Montana (CNN) -- There doesn't seem to be any one issue driving voters to the polls here in Montana.

One voter told me he voted for incumbent Republican Sen. Conrad Burns because he thought his opponent, Democrat Jon Tester, would raise his taxes. Another voter told me he voted for Tester because he felt Burns had sold out the environment to big oil companies. And then there are the voters who just want "something different" -- which, in this case, is akin to a vote against Burns.

I asked them what they meant by that: Do they really like Tester? A few said they do. But two people said, "Nah, he's just OK. But things aren't right. We need a change."

Sen. Burns has been in office for 18 years, but he's in the toughest fight of his career. Tester is a 3rd generation farmer who's going after some of those rural and conservative voters other Democrats had written off in years past.