Washington’s 4th congressional district features an open seat after longtime Republican incumbent Dan Newhouse retired, pitting Republican Amanda McKinney against Democrat John Duresky in the November general election. McKinney emerged from the August top-two primary with a modest edge in vote share and far stronger fundraising, while the district’s consistent Republican presidential margins provide a structural advantage. Trader pricing across margin buckets reflects uncertainty over final spread, driven by turnout patterns in agricultural and reservation counties, limited public polling, and the absence of major late-cycle developments that could widen or narrow the gap. Early voting underway offers one near-term data point that could shift implied probabilities on specific ranges.