Former U.S. Rep. Mike Rogers commands 92.5% implied probability on Polymarket as the Michigan Republican Senate primary frontrunner, bolstered by a major April 6 announcement from the Senate Leadership Fund committing $45 million—the group's largest early investment in a non-GOP-held seat—to aid his bid in the open race following Sen. Gary Peters's retirement. This follows a March endorsement and $15 million from Sentinel Action Fund, amplifying Rogers's fundraising edge, name recognition from his 2024 near-miss against Elissa Slotkin, and establishment backing including past Trump support. With minimal challengers like Kent Benham polling low and no recent GOP primary surveys showing competition, traders see scant path for upsets absent a late high-profile entrant, scandal, or ballot access issues before the August 4 primary.