Incumbent Senator Max Baucus won re-election to a sixth term in a landslide, winning more than 70% of the vote and carrying every county in the state, despite Republican John McCain's narrow victory in the state in the concurrent presidential election.

Montana generally gives its presidential electors to Republican candidates, but historically has elected several prominent Democrats to the United States Senate, including Thomas Walsh, Burton K. Wheeler, Mike Mansfield, and Lee Metcalf.

It was revealed that Garnett Shay had an outstanding warrant for his arrest, preventing him from running an effective campaign.

[2] Senator Baucus defeated Kelleher as a Democratic incumbent running in a year that was very successful for his party in general.

Kelleher, a perennial candidate and eccentric figure in Montana politics, took many positions that were highly unorthodox by GOP standards, such as favoring more liberal drug control policies, supporting universal healthcare and affirmative action, and favoring fair trade restrictions.