The Democratic Party’s internal dispute over Medicare for All has reached this battleground state, and so far, supporters of a single-payer health care system are finding a tough audience. Union members in this labor stronghold state have expressed unease with Medicare for All, fearing they would lose health benefits that were hard-won over years of negotiations. A survey of 600 likely voters commissioned by the Detroit Regional Chamber this summer found that a majority opposed a Medicare for All proposal that would eliminate private health insurance, as proposed by Democratic presidential candidates Elizabeth Warren and Bernie Sanders. Kamala Harris, a...