2025 Kostroma Oblast legislative election
12–14 September 2025
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All 35 seats in the Oblast Duma 18 seats needed for a majority | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Turnout | 39.72% 7.75 pp | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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The 2025 Kostroma Oblast Duma election took place on 12–14 September 2025, on common election day, coinciding with 2025 Kostroma Oblast gubernatorial election. All 35 seats in the Oblast Duma were up for re-election.
United Russia increased its already overwhelming majority in the Legislative Assembly, winning 50.3% of the vote and 21 of 25 single-mandate constituencies. Liberal Democratic Party of Russia came in second, doubling its faction to two deputies. Communist Party of the Russian Federation and A Just Russia – For Truth saw their vote share decreasing by roughly a third, however, CPRF retained its two-member faction, while SR–ZP even gained one more seat in a single-member constituency.