– Political groups fighting for control of the U.S. Senate have poured more than $118 million into the contest between Montana's Democratic Gov. And the Montana political ad spending is almost 10 times as much per voter being spent on ads in Colorado's Senate contest between former Democratic Gov. But the main driver is the race's competitive nature and the high stakes in the Senate. “These groups that are spending, they're spending big," Bullock told The AP. The Annenberg center's Jamieson, whose grandmother homesteaded in Montana, noted that political ads have a long history in the state.