Bruce Lunsford

The U.S. Senate race in Colorado is being held up elsewhere as an example of 527 group influence in Senate campaigns.

Bruce Lunsford, the Democratic U.S. Senate nominee in Kentucky, said Tuesday, talked about how, as in his race against Senate Minority Leader Mitch McConnell, Republican 527s are outspending Democrats in Colorado.

"Mark Udall is really a nice guy and a good candidate and he was probably up 15 points out here at one point, and they've outspent him seven to one," Lunsford said. "I saw three commercials this morning in a half an hour on the same station with all those 527 funds and all that extra money and they've tightened this race up out here as a result.

"So I think that you've got to know what you are fighting against with the Republicans," he said. "They play dirty pool, they do everything they can."