Recent Republican midterm losses have widened the 2028 GOP nomination field and elevated Robert F. Kennedy Jr. to the leading position in trader consensus at 49 percent. His Make America Healthy Again movement and distance from recent administration setbacks have drawn significant betting interest. Vice President J.D. Vance sits at 30.8 percent after his standing slipped amid the party's electoral setbacks and questions about his path forward. Secretary of State Marco Rubio holds 18.1 percent as a steady alternative with broad institutional ties, while Florida Governor Ron DeSantis has climbed to 16 percent by highlighting state-level successes and post-election positioning. These probabilities reflect traders weighing polling trends, primary dynamics, and potential endorsements in a still-fluid contest.