LANSING, Mich. — Gov. Gretchen Whitmer is launching a four-day bus tour across Michigan with Democrat Joe Biden’s presidential campaign before the Nov. 3 election. No passengers will actually be on the bus, due to the coronavirus pandemic. Democrats instead will travel in a vehicle caravan. The tour starts Friday in Taylor, a Detroit suburb, with a rally hosted by Lt. Gov. Garlin Gilchrist II and U.S. Rep. Debbie Dingell. Whitmer, a co-chair of Biden’s campaign, plans to appear at some events over the four-day period. Stops will include car rallies, sign distributions, early-voting sites, absentee ballot drop boxes and volunteer mobilization events.