Lansing — Metro Detroit businessman Kevin Rinke, a Republican, is planning an initial investment of $10 million in his potential campaign for governor, an adviser said Monday, the day candidates already in the race had to file their first fundraising disclosures. Rinke of Bloomfield Township, whose family has owned and operated auto dealerships in the state, has previously said he's "seriously considering" running for governor. His ability to self-fund his campaign could give him an advantage over the current field of GOP competitors and the chance to immediately cut into the large fundraising lead of incumbent Democratic Gov. Gretchen Whitmer. Michigan's last Republican governor, Rick Snyder, used about $6 million of his own wealth to boost his campaign in the 2010 primary.