Virginians cast ballots Tuesday on a proposed congressional map that would aggressively gerrymander the state in the Democrats’ favor, giving the party as many as four extra U.S. House seats.

The new map would draw eight safely Democratic districts and two competitive districts that lean Democratic, according to a New York Times analysis of 2024 presidential results. It would leave just one safe Republican seat, compared with the five seats the G.O.P. holds on the current map.

The proposed map was drawn by Democratic state legislators and approved by Gov. Abigail Spanberger, a Democrat. It would eliminate three Republican-held seats in part by slicing the densely populated suburbs in Arlington and Fairfax Counties and reallocating their overwhelmingly Democratic voters into five congressional districts, some stretching more than a hundred miles into Republican areas.

Perhaps the most extreme new district would be the Seventh, which begins at the Potomac River and stretches to the west and south in a manner that resembles a pair of lobster claws. Several well-known Virginia Democrats have already announced their candidacies and begun campaigning in the district.

Reid J. Epstein contributed reporting.