Delaware Republican Senate Primary Odds: Michael Katz Remains Heavy Favorite Ahead of Tuesday's Vote
Delaware’s Republican Senate primary pits former state senator Michael Katz against military veteran John Shulli on Tuesday night. Can Shulli overcome the favorite to secure the GOP nomination? Check out the latest Delaware Republican Senate primary odds and candidate breakdown for Tuesday, September 15.
Peter Alexis - September 15, 2026, 7:10 PM EDT
4 Minute ReadMichael Katz Man to Beat in Delaware Republican Senate Primary on Tuesday, September 15th
Delaware Republicans head to the polls Tuesday, September 15, with Michael Katz holding a commanding prediction-market advantage over John Shulli. Katz sits at 87% to secure the Republican U.S. Senate nomination, while Shulli carries a 14% chance of delivering an upset.
The market has shown relatively little movement throughout the afternoon, with Katz consistently maintaining a substantial lead. These percentages reflect expectations about who will win the nomination, rather than projected vote shares, and Tuesday’s winner still faces the separate challenge of competing for the Senate seat in November.
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Latest Delaware Republican Senate Nominee Odds From Kalshi
Candidate | Implied Probability |
|---|---|
Michael Katz | 87% |
John Shulli | 14% |
Michael Katz (87%)
Katz brings a mix of medical, business and legislative experience to the race. A physician and former Democratic state senator, he served in Delaware’s legislature from 2009 to 2013 and later ran for U.S. Senate as an independent in 2024. His Republican campaign emphasizes affordability, health care reform and federal fiscal discipline.
The Delaware Republican Party’s endorsement gives Katz an important organizational advantage, particularly in a primary where mobilizing committed voters matters. His political history also creates an interesting test: Can a candidate who previously represented Democrats consolidate Republican support? At 87%, the market strongly expects him to clear that hurdle, although his nomination would leave the much harder task of winning statewide in November.
John Shulli (14%)
Shulli offers voters a military and national security background, having reached the rank of Army colonel and served as a part-time instructor at the U.S. Army War College. His campaign priorities include higher wages, government accountability and parental rights in education.
At 14%, Shulli enters Tuesday night as the clear underdog. His route to an upset depends on translating his leadership credentials and conservative platform into stronger support among Republican primary voters than traders anticipate. The displayed market has remained stubbornly tilted toward Katz, leaving Shulli needing an election-night surprise rather than simply extending an established late surge.
Delaware Republican Senate Primary Outlook
Katz is the clear market favorite, but the size of his actual winning margin, if he prevails, remains an open question. The available odds establish expectations about the outcome without demonstrating how closely the candidates are running among voters.
Polls close at 8 p.m. Eastern on Tuesday. The winner advances to the November 3 general election for the seat currently held by Democrat Chris Coons, who also faces a primary. For this nomination contest, the central question is whether Katz’s party backing and political experience produce the expected result or whether Shulli can turn his underdog campaign into a surprise.
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