JD Vance holds a commanding lead in 2028 Republican presidential nomination polling and prediction markets, with recent surveys showing him ahead of Marco Rubio by double-digit margins among GOP voters. Rubio, serving as secretary of state, has signaled support for Vance as the likely nominee and has no announced plans to challenge him. Vance strengthened his position through strong convention performances and consistent frontrunner status in early assessments, while Rubio remains focused on diplomatic duties. With the October 31 deadline weeks away and no scheduled events poised to shift the field dramatically, traders assign near-certain odds against any immediate reversal. Late developments such as a major scandal, unexpected Trump intervention, or rapid polling movement could theoretically alter positioning, though none appear imminent in current reporting.