In the low-salience 2026 Delaware U.S. Senate contest, where incumbent Democrat Chris Coons faces Republican Michael Katz in a race rated Solid Democratic, trader probabilities cluster tightly across the 325K–425K turnout bands. The September 15 primary produced roughly 129,000 ballots from 593,000 registered voters, reflecting limited campaign intensity and historical midterm participation patterns in a state with a modest eligible voter pool. Democratic registration advantages and expanded early voting support baseline engagement, yet the absence of competitive statewide races or national flashpoints has produced no strong mobilization signals. Primary results showing Katz’s nomination, late national developments, election-day weather, or intensified get-out-the-vote efforts in key counties could widen separation among the leading ranges before November 3.