Michael Katz holds a commanding lead in the Delaware Republican U.S. Senate primary, scheduled for September 15, 2026, due to endorsements from the state Republican Party, former U.S. Attorney Julianne Murray, and multiple legislators, along with his background as a physician, business owner, and former state senator. These factors have consolidated support among party regulars and positioned him as the candidate best equipped to appeal beyond the GOP base in a heavily Democratic state. John Shulli, a retired Army colonel and instructor at the U.S. Army War College, has drawn backing from figures such as Michael Flynn and one state legislator but trails in organizational support and fundraising momentum. With one week until voting, trader consensus reflects Katz’s structural advantages; a late scandal, unusually low turnout among his coalition, or unexpected base mobilization for Shulli represent the narrow paths that could alter the result before certification.