The Michigan Democratic Party wants the Internal Revenue Service to examine a Republican Senate candidate’s $500,000-a-year compensation from a nonprofit group, says the Detroit Free Press.

Mark Brewer, the state’s Democratic Party chairman, claimed Wednesday that Clark Durant was paid for work on behalf of a nonprofit Detroit education network via a “sham charity” called the Genesis Foundation. Mr. Durant is one of three Republicans competing in the Aug. 7 primary, the winner of which will take on Sen. Debbie Stabenow, a Democrat.

Mr. Durant helped found the Cornerstone Schools Association, for which his daughter, Hope Durant Loomis, serves as chief development officer. They have long been paid for their Cornerstone work through Genesis, which is primarily supported by two wealthy businessmen and puts 95 percent of its revenue toward Mr. Durant’s and Ms. Loomis’s compensation.

Mr. Brewer called the arrangement a “blatant violation” of IRS rules against operating a nonprofit group for the purpose of private enrichment. Mr. Durant said his relationship with Genesis, which was formed specifically to support Cornerstone, has been above board and was forged to avoid the appearance that he was raising money for Cornerstone to pay his own wages.