HELENA (AP) — Outside groups have already spent millions of dollars on ads attacking either Democratic Sen. Jon Tester or Republican Rep. Denny Rehberg in Montana's high-profile Senate race.
Lee Newspapers of Montana reports that three groups have spent more than $1.5 million on broadcast advertisements that go after Tester, while three other groups have spent $720,000 on anti-Rehberg ads.
Various other groups have spent between $800,000 to $1 million on ads attacking or supporting either candidate.
That's only the beginning, political observers say.
"My rule of thumb is that they want to ramp up (the spending) when you get closer to the election," said David Parker, a Montana State University political scientist. "So if you've seen this much (spending) a year out ... that's just a taste of what's coming."
The Rehberg-Tester race is among the most closely watched in the country, with Democratic control of the Senate in the balance.
Almost all of the ads are sponsored by nonprofit groups that do not have to reveal who finances them. The ads are known as "issue-advocacy" spots, which don't say to vote for or against a candidate but instead mention the candidate's name in connection with an issue.
While the law prohibits these groups from coordinating with the campaign of the candidate they're assisting, their attacks often mirror those mounted by their favored candidate.
The prominent anti-Tester ads so far have come from the U.S. Chamber of Commerce, the 60 Plus Association and Crossroads GPS, a conservative group with links to former President George W. Bush adviser Karl Rove.
The 60 Plus ad, which features former singer Pat Boone, blasts the federal health reform law and Tester's support of it, which has been a central theme of Rehberg's campaign.
A group called Citizens for Strength and Security and two wildlife and hunting groups have been behind most of the anti-Rehberg ads. The Citizens for Strength and Security ads have criticized Rehberg for accepting congressional pay raises, an issue the Tester campaign has focused on.
Tester has denounced the third-party ads running against him, saying big-money interests are trying to buy the election.
"We encourage all Montanans to see what organization is responsible for any third-party ad," said Tester's campaign spokesman, Aaron Murphy. "Who is it? What do they stand for? Who bankrolls them?"
Rehberg's campaign also is critical of the groups taking him on but says it is confident voters will see through what it calls misleading messages.
"Montanans know the truth when they see it, and voters will ultimately make an informed decision based on whether they agree more with Denny's ideas for spurring free enterprise to create jobs, or Sen. Tester and President Obama's agenda of a bigger, more costly government in Washington," said Rehberg campaign spokesman Chris Bond.