United Russia’s dominant position as Russia’s ruling party underpins the 65.5% implied probability that it secures majorities across all 39 regions holding legislative elections on September 18–20. The party benefits from presidential administration coordination on candidate lists, favorable ballot positioning in more than half the regions, and registration barriers that have narrowed competition, with fewer opposition parties fielding full slates than in prior cycles. Putin’s public endorsement at the June party congress and regional outreach have reinforced organizational advantages, while forecasts from Russian analysts project the party retaining or expanding control everywhere amid limited credible challengers. Historical precedent of near-universal regional victories and the absence of major recent disruptions sustain trader expectations, though minor seat losses in select areas remain possible within the tightly managed system.