The long-running battle between unions and Wisconsin Gov. Scott Walker (R) got even "dirtier" this week, with one union official accusing him of violating workplace safety regulations in his new campaign ad.

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The ad (below) shows Walker standing in a dirt hole, claiming that his opponent's policies will put the state in a "pretty big hole."

He then climbs out using a ladder, but wearing no helmet or protective gear.

According to the Wisconsin State Journal:

Jeff Kaminiski, president of United Steelworkers Local 2006, said this week he called the Occupational Safety and Health Administration’s Madison office and asked that Walker be fined.

“Gov. Walker’s violations send the wrong message to anyone trying to follow the rules and come home safe at the end of the day,” Kaminski said in a statement. “Safety is the backbone of the union movement. We want all workers to come home safe at the end of the day. We can’t have an example like this playing statewide.”

The ad, in which Walker says Burke got Wisconsin “in a pretty big hole,” does illustrate multiple violations of OSHA rules for working in trenches, said Adam Finkel, executive director of the Penn Program on Regulation at the University of Pennsylvania and a former OSHA director of health regulations under President Bill Clinton.

The hole isn’t properly reinforced, the ladder is too short and Walker isn’t wearing safety goggles or a helmet, he noted.

“There does seem to be a pattern here of people who are indifferent to worker health and safety, or actively not helping the cause, or opposed to the cause, tending to use these metaphors thoughtlessly,” Finkel said.

But it’s unlikely Walker would be fined or even investigated by OSHA, Finkel said.

He pointed out that formal OSHA complaints are usually made by or on behalf of employees against an employer. Alternatively, anyone can refer potential workplace violations to OSHA for follow up, but with 2,000 inspectors and 8 million sites, “they’re not in the business of retroactively citing someone for something that no longer exists.”

“A complaint has to be about a work site that’s ongoing,” Finkel said. “Just because it’s documented on film doesn’t mean there will be a citation. ”

In 2011, Walker sparked mass demonstrations by union workers by cutting benefits for public employees and targeting collective bargaining rights. A year later, Walker survived a recall election.

Walker is running for re-election against Democrat Mary Burke.

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