DETROIT — Democrats are deploying prominent Black surrogates to Michigan to deliver an urgent plea: Black men, we need you. It’s a concerted push, involving the likes of NBA hall-of-famer Magic Johnson, New York Attorney General Tish James, Democratic Party elder Rep. Jim Clyburn (D-S.C.), Gen-Z Rep. Maxwell Frost (D-Fla.) and actress Kerry Washington in Detroit, which is nearly 80 percent Black, and the surrounding area. And it’s the latest sign that the Kamala Harris campaign — and Democrats more broadly — see trouble on the horizon. Harris has built up a small advantage in Michigan, but soft turnout among Black voters could cause…