Sen. Richard Lugar Calls Primary Rival Richard Mourdock A Liar In Ad

Sen. Richard Lugar (R-Ind.) has fired another round in his increasingly bitter primary battle with Indiana state Treasurer Richard Mourdock, calling his rival a liar in a new ad.

"Richard Mourdock is attacking Dick Lugar again, now intentionally misrepresenting Lugar's record on Obamacare," the ad says, referring to recent charges by Mourdock. "Typical politician. Mourdock knows the truth. Lugar voted against Obamacare 32 times."

When they resort to negative ads, it is often a sign that front-running campaigns -- like Lugar's at the moment -- are worried. Indeed, a pair of polls released Monday by Democratic and Republican opponents of Lugar both found Mourdock has climbed to within 6 percentage points of Lugar, even though the incumbent senator remains broadly popular.

Part of Lugar's problem lately has been the pounding he's taken from both sides over the fact that he lives in Virginia, not Indiana. A local election commission ruled last week that he is not eligible to vote in his former hometown, although state officials have declared that he is eligible to run.

WATCH the new ad: