UNDATED (AP) -- This AP digital embed shows congressional apportionment gains and losses resulting from the 2020 census.

Sources: Brookings Institution, Brace of Election Data Services, Census

The U.S. Census Bureau is aiming to deliver the long-delayed numbers used for divvying up congressional seats by the end of April. But a holdup on redistricting data could disrupt several states' abilities to redraw their own legislative maps ahead of upcoming elections.

Census Bureau official Kathleen Styles said Wednesday that the bureau needs time to fix any data irregularities.

The delay in the release of redistricting data could be problematic for states that have deadlines this year for redrawing their districts. That includes New Jersey and Virginia, which have elections this year.

Experts say some states have already started working on backup plans.

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