American Crossroads v. Pryor

The Weekly Standard reports:

Conservative super PAC American Crossroads has a new ad running in Arkansas calling Democratic senator Mark Pryor a "rubber stamp" for Barack Obama.
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American Crossroads founder Karl Rove says the group is spending $440,000 on the ad buy.

Pryor is up for reelection this November and faces first-term Republican congressman Tom Cotton, who is giving the incumbent Democrat a tough fight. The Real Clear Politics poll average shows Pryor and Cotton locked in a virtual dead heat, with Pryor holding a one-point advantage.