A conservative outside group is airing ads attacking Sen. Mark PryorMark Lunsford PryorMedicaid rollback looms for GOP senators in 2020 Cotton pitches anti-Democrat message to SC delegation Ex-Sen. Kay Hagan joins lobby firm MORE (D-Ark.) for backing President Obama's judicial nominations.

The ad, from the Judicial Crisis Network, hits Pryor for supporting Obama's nominations to the Supreme Court and D.C. District Court and attacks him as a "rubber stamp" for Obama's agenda.

"Mark Pryor voted for every one of Obama's liberal activist judges — every single one. Now Pryor is helping Obama pack a key court with new liberal judges who will review the EPA, the IRS and agencies Obama is using to push his unconstitutional, job-killing agenda. When Mark Pryor rubber-stamps Obama's liberal judges, it hurts Arkansas. Enough is enough. Tell Mark Pryor to go to work for Arkansas, not Obama."

The ad, which is running in the Little Rock media market, is the latest attack against Pryor in what's quickly turned into the highest-volume air war of any Senate race in the country.

Pryor's campaign fired back, pointing out that he's voted 73 times against Obama nominees and voted 123 times for judicial nominees of President George W. Bush.

"Another day, another false attack from Tom CottonThomas (Tom) Bryant CottonGOP senator: Supreme Court abortion cases were 'wrongly decided as a constitutional matter' Senate confirms controversial 9th Circuit pick without blue slips Cotton: US could win war with Iran in 'two strikes' MORE's Washington special interest pals trying to smear Mark Pryor because he looks after Arkansans," says Pryor spokesman Erik Dorey.