MADISON, Wis. -

Republican U.S. Senate candidate Eric Hovde is raising concerns over a new attack ad against him by an independent group that is a client of the same firm running Tommy Thompson's campaign.

The Americans for Job Security ad began running on Thursday.

Americans for Job Security is listed as a client of Persuasion Partners, a consulting firm running Thompson's campaign.

Hovde spokesman Sean Lansing said Friday that connection smacks of illegal coordination. He is calling on Thompson to either stand behind the ad's attacks or call on the group to disclose its donors.

Darrin Schmitz, president of Persuasion Partners and a consultant to Thompson's campaign, said he did work for the group four years ago but nothing since. He calls the Hovde accusation "a cheap shot from a desperate campaign."