California voters in 2010 gave the power to draw congressional maps to an independent commission, with the goal of making the process less partisan. The commission last redrew maps following the 2020 census, and the maps were in place for the 2022 and 2024 U.S. House elections.

Democrats who run populous states are considering redistricting, but some of them face a hurdle: Their parties don’t have control over drawing legislative maps. Instead, the power is in the hands of independent commissions, something often left-leaning pro-democracy advocates have supported to enact fair maps that reduce gerrymandering.