Two leading figures in Donald Trump's Republican Party — Vice President JD Vance and Secretary of State Marco Rubio— could shape the future of US global leadership. While both criticize globalization and current alliances, their approaches differ sharply: Vance favors a more restrained, inward-focused US, shaped by his Rust Belt upbringing; while Rubio, influenced by his family’s exile from Cuba, supports strong international engagement. Their contrasting visions could significantly impact alliances, conflicts and global stability.