Trader consensus on Polymarket assigns Robert F. Kennedy Jr. the leading 49 percent implied probability for the 2028 Republican presidential nomination, ahead of Vice President J.D. Vance at 38.1 percent and Marco Rubio at 20.3 percent. This reflects Kennedy’s cabinet role and emphasis on health and regulatory policy alongside Vance’s visibility as the sitting vice president and Rubio’s position as a senior administration official. The remainder of the field, including Ron DeSantis at 3.8 percent and Tucker Carlson at 3 percent, trades at single-digit or lower levels consistent with limited declared interest or polling momentum this far ahead of the primaries. The November 2026 midterms and any subsequent administration developments could supply further signals for traders evaluating the contest.