Attorney General Chris Koster (PoliticMo Photo)

— Attorney General Chris Koster released a new campaign television commercial on Thursday attempting to define his rival, Republican Ed Martin, as a corrupt politician.

The ad, entitled “Billboards,” makes an implicit reference to Martin’s set of billboards across the state denouncing Koster as “Obama’s Lawyer.” But instead of touting Martin’s messaging, Koster’s ad features “billboards” touting newspaper editorials critical of Martin.

“Citizens for Responsibility and Ethics called Martin one of the most corrupt politicians in America,” the narrator said. “While Martin might not want to advertise that, we thought voters deserve to know.”

Koster’s latest critical ad is his second direct attack on Martin. His first came in an ad released last week that detailed Martin’s involvement in an email deletion scandal during Gov. Matt Blunt’s tenure.