John E. Sununu's commanding position in the New Hampshire Republican Senate primary stems from his prior service representing the state in the U.S. Senate from 2003 to 2009, combined with the Sununu family's deep political roots through his brother, former Governor Chris Sununu, and father, former Governor John H. Sununu. President Trump's February endorsement as an "America First patriot" has further unified party support, while national Republican super PACs have backed his campaign. Recent polling averages show Sununu at 55-60% against Scott Brown's roughly 20%, with Dan Innis withdrawing to endorse him and Chris Sununu declining to run. With the September 8 primary just days away, this polling and institutional backing explain the market's 97.4% implied probability for Sununu. Only unforeseen late developments, such as a major scandal or health issue, could realistically shift the outcome in the final stretch.