MADISON, Wis. (AP) — The Wisconsin Republican Party on Wednesday called on Democratic candidate for governor Mahlon Mitchell to explain a 19 percent salary increase he received last year as head of the state firefighters union, as well as political donations made by the union to benefit Mitchell and other liberal advocacy groups.

Mitchell, one of eight Democratic candidates on Tuesday's primary ballot, said the criticism showed GOP Gov. Scott Walker was afraid of him. The winner of the Democratic primary will advance to face Walker in November.

"Again, Scott Walker is rolling out his divide and conquer playbook of the past," said Mitchell's campaign spokeswoman Kirsten Allen. "He's clearly afraid of Mahlon and the coalition we've built behind a campaign focused on Wisconsin rising together."

Mark Morgan, executive director of the Wisconsin Republican Party, accused Mitchell of misusing firefighter union dues as president of the Professional Fire Fighters of Wisconsin to turn the union into his "own personal slush fund."

"What we have seen thus far is serial misuse and abuse of funds with the clear intent of guiding union funds for personal and political benefit," Morgan said.

Mitchell, a Madison firefighter, has been the union's leader since 2011.

In 2017, Mitchell's salary increased 19 percent to $115,080. Taken together with his salary from the Madison Fire Department, Mitchell made $220,501 last year. The governor is paid $144,423 a year.

Mitchell's campaign referred all specific questions about his salary and work for the union to Steve Wilding, the secretary/treasurer for the union. Both he and Mitchell were in Seattle on Wednesday for the international union's convention.

Wilding did not immediately respond to an email with questions. But he told the Milwaukee Journal Sentinel earlier Wednesday that Mitchell's base salary dropped from $90,000 in 2016 to $70,000 in 2017 and that the rest of his payment was for services performed for the union on a day-to-day basis.

Morgan questioned $130,000 spent by the union to help Democratic candidates or liberal causes. The union has given just over $40,000 to Mitchell's gubernatorial campaign and its political action committee has given another $86,000, the maximum allowed under the law.

Morgan also said Mitchell needs to explain a $38,000 lawsuit settlement paid by the union to former staffer Andrea Belton in March 2014. Wilding told the Journal Sentinel the dispute did not involve Mitchell. Belton told the newspaper that the payment was for unused time off and office equipment, declining to elaborate on why the payment was so big.

Also, the Republican Party pointed to a Department of Labor audit from 2015 that faulted the union for not adequately documenting $69,000 in expenses, not having a clear credit card reimbursement policy, having no limits on reimbursements for food and alcohol, and failing to have a policy for the payment of per diems to union officers for official union work.

"Time and again Mitchell has shown that he put his own personal political ambitions ahead of his members, and would no doubt act the same way as governor," Morgan said.

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