Marco Rubio leads the 2028 Republican vice presidential nomination market at 29.5% due to his high-profile role as Secretary of State, which has raised his national profile through diplomatic work, combined with repeated suggestions from President Trump of a potential Vance-Rubio ticket. Vice President J.D. Vance, the clear frontrunner for the presidential nomination in polling averages and other markets at around 45-55%, trades far lower for VP at 5.5% as traders expect him to seek the top spot. The fragmented field below 7% reflects uncertainty over the eventual presidential nominee, ticket-balancing needs, and divided support among Senate, gubernatorial, and media figures. Rubio’s foreign policy experience and Senate tenure stand out as differentiators for balance, while consolidation behind one outcome would likely require the presidential nominee’s selection, post-midterm polling shifts, or a Trump endorsement.