Congressman Dave Obey is calling on Alex Paul to pull an ad that attacks his opponent in the primary election.
Democrats Alex Paul and Representative Julie Lassa are facing off for the 24th senate seat that Kevin Shibilski vacated when he became the tourism secretary.
Paul's ad blasts Lassa for accepting special interest money and links her to embattled democratic state senator Chuck Chvala.
Chvala faces 20 felony charges for extortion and official misconduct. Nearly two years ago Chvala attended a fundraiser for Lassa.
Congressman Obey says the ad is the worst kind of politics reminiscent of Joe McCarthy because it uses guilt by association.
Obey says he does not endorse either candidate, but it is his responsibility to make sure the race is clean and fair.
Both Lassa and Obey have called for the ad to be pulled, but Alex Paul's campaign says everything in the ad is true and they won't pull it off the air.