Michael Katz holds a commanding lead in the Delaware Republican U.S. Senate primary due to his endorsement by the state Republican Party and key figures including former U.S. Attorney Julianne Murray, along with several sitting and former state legislators. His background as a former Democratic state senator, physician, and business owner has enabled him to build a coalition spanning Republicans, independents, and some crossover voters in a heavily Democratic state. John Shulli, a retired Army colonel and faculty instructor at the U.S. Army War College, draws support from a narrower base focused on national security and military credentials, including an endorsement from Michael Flynn, but lacks comparable institutional backing. With the September 15 primary just days away, traders view Katz's fundraising, party infrastructure, and prior statewide ballot experience as decisive advantages over Shulli's profile.