The League of Conservation Voters on Thursday kicked off a nearly $1 million TV ad campaign against Republican Senate candidate Rep. Cory Gardner (R-Colo.), a sizable buy against a top GOP Senate recruit.

The ad hits Gardner for taking contributions from the oil and gas industries and claims that he "sides with them."  Gardner "is out of step with Colorado," the narrator says.

The group is spending at least $975,000 over the next two weeks on the Colorado airwaves, mostly on broadcast television.

Gardner announced in February that he would challenge Sen. Mark Udall (D-Colo.), instantly making the race more competitive for Republicans.