MADISON, Wis. (AP) — A group founded by conservative billionaires Charles and David Koch is attacking seven county board candidates in Wisconsin as "radical anti-mining" environmentalists. The candidates are running in Iron County, where Gogebic Taconite has plans to open an iron mine. The campaign launched Wednesday by Americans for Prosperity is attracting attention in sparsely populated Iron County, where candidates themselves don't usually campaign. Town of Saxon Assistant Fire Chief Karl Krall is one of the people running for the county board. He says he is perplexed by the mailing because he is a strong mine proponent and has made appearances with Gov. Scott Walker in support of the mine. Krall says the Americans for Prosperity campaign is "a joke."