Conservative super PAC American Crossroads has a new ad running in Arkansas calling Democratic senator Mark Pryor a "rubber stamp" for Barack Obama.

"Mark Pryor has voted with Barack Obama at least 90 percent of the time," says the voiceover in the 30-second spot. "For the failed stimulus, for higher taxes, more spending, trillions more in debt, and more job-killing regulations. And Pryor cast the deciding vote for Obamacare."

Watch the full ad below:

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.

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