Club for Growth endorsed Ken Buck in August following a primary victory over former Colorado Lt. Governor Jane Norton.

Now, Club for Growth has launched a TV ad against Sen. Michael Bennet, part of a $1.5 million slate of ads targeting a handful of vulnerable Senators, including Senate Majority Leader Harry Reid (D-NV).

“What’s happened to Michael Bennet?” the ad opens rhetorically. “After only 18 months in Washington, he acts like he’s been there forever”:

Pollster.com’s rolling average of poll results in the U.S. Senate race: