Voters in Virginia went to the polls Tuesday to decide whether to approve a new congressional map drawn by Democrats, a measure that could shift several Republican-held seats and influence the balance of power in the U.S. House of Representatives.

The proposed map would significantly alter district boundaries across the state, where Democrats currently hold six of 11 House seats. If approved, analysts say the new configuration could give Democrats an advantage in nearly all but one district, potentially flipping up to four Republican seats in the November elections.

The referendum comes amid a broader nationwide redistricting conflict that intensified after President Donald Trump backed efforts by Republicans in Texas to redraw maps targeting Democratic incumbents. Since then, both parties have pursued aggressive redistricting strategies in states they control, raising the stakes in closely divided congressional races.

Control of the House remains narrowly contested, with Democrats needing to gain just a handful of seats to reclaim a majority. Such a shift would allow them to launch investigations into the administration and block elements of the president’s legislative agenda.

The Virginia measure has attracted heavy spending from outside groups. A Democratic-aligned organization, Virginians for Fair Elections, raised more than $64 million as of mid-April, while the main Republican-backed opposition group, Virginians for Fair Maps, reported roughly $20 million in funding.

Legal challenges from Republicans have also surrounded the referendum, though the Virginia Supreme Court allowed the vote to proceed while reviewing the case.

The issue has drawn national attention, with both parties framing the referendum as part of a larger fight over partisan gerrymandering. Democrats argue the map is a response to similar efforts in Republican-led states, while Republicans accuse Democrats of reversing their prior opposition to politically driven redistricting.

Prominent political figures have also entered the debate. Former President Barack Obama has urged voters to support the measure, while Republicans have highlighted his past criticism of gerrymandering in campaign messaging opposing it.

The outcome in Virginia could have ripple effects beyond the state, as additional redistricting battles loom. Florida Gov. Ron DeSantis has called for a special legislative session to consider changes to his state’s congressional map, and the U.S. Supreme Court is expected to issue rulings that could further shape how districts are drawn nationwide.

With control of Congress potentially hinging on a small number of seats, the Virginia vote represents one of the most closely watched political contests in the current election cycle.