"Those out-of-state super-PACs don't know anything about me or Montana," he says, a nod to what Reuters reports are the 14 outside groups spending money in the race, much of which has been employed in an attempt to tie Tester to Obama.

Such a strategy, Republicans hope, could play well in a state President Obama lost in 2008. And Tester remains slightly behind challenger Rep. Denny Rehberg (R-Mont.) in most polls, though he's within the margin of error and could conceivably overcome the congressman before November.

The ad is backed by a $100,000 buy and will run statewide.