While Joe Biden and Donald Trump are marching toward their respective presidential nominations, Michigan's primary on Tuesday could reveal significant political perils for both of them.
Trump, despite his undoubted dominance of the Republican contests this year, is facing a bloc of stubbornly persistent GOP voters who favor his lone remaining rival, former U.N. Ambassador Nikki Haley, and who are skeptical at best about the former president's prospects in a rematch against Biden.
