A Virginia court has blocked the implementation of new congressional district maps in the state, The Guardian reported on Thursday, ruling the act unconstitutional following a lawsuit by the Republican National Committee (RNC).

Virginia voters on Tuesday had approved a new Democratic-drawn congressional map that could flip four Republican US House seats in November's midterm elections, US media projected, dealing a fresh blow to Republicans' tenuous chances of holding their narrow majority.

The special election was the latest battle in an unprecedented coast-to-coast redistricting fight that began last summer, when US President Donald Trump successfully urged Texas Republicans to adopt a new congressional map that targeted five Democratic incumbents.

The outcome had added to Democratic momentum following a string of impressive performances in dozens of elections since Trump took office last year, bolstering Democratic Virginia Governor Abigail Spanberger, whose own 15-point victory in November was widely read as an early warning for Republican prospects this fall, and who had campaigned in favor of the measure.

The updated district lines would likely result in Democrats capturing 10 of the state's 11 seats in the US House of Representatives in November, up from their current six-to-five advantage.

Democrats need to flip only three Republican-held seats nationwide in November to win control of the 435-seat House, which would enable them to investigate the Trump administration and block the president's legislative agenda.

Reflecting the stakes, both parties had poured tens of millions of dollars into the Virginia race, with Democrats spending far more than Republicans. Most of the funds have come from so-called "dark money" political groups that are not required to disclose their donors.

The main organization backing the ballot measure, Virginians for Fair Elections, raised $64.1 million through April 13, the latest deadline for campaign finance reporting. More than $38 million came from House Majority Forward, House Democrats' main political nonprofit arm.

The leading Republican-led opposition group, the similarly named Virginians for Fair Maps, had brought in nearly $20 million as of April 13.

Trump had exhorted Virginians to vote against the measure early on Tuesday, writing on social media, "VIRGINIA, VOTE 'NO' TO SAVE YOUR COUNTRY!"

The referendum amends the state constitution to allow lawmakers to sideline an independent redistricting commission until 2030, when the power to draw congressional lines would revert to the commission.

Redistricting typically occurs at the end of each decade to reflect population changes recorded in the US Census. State lawmakers have historically used that process to draw districts that are more favorable to their party, a strategy known as partisan gerrymandering.

Democrats argued the new map was necessary to counter Texas and other Republican states that have used redistricting to target Democratic seats at Trump's behest. Republicans accused Democrats of hypocrisy, pointing to their previous stances against partisan gerrymandering.

Republican Florida Governor Ron DeSantis has called a special session next week to consider redrawing the state's map, and the US Supreme Court is still weighing a voting-rights case that could allow Republicans in southern states to target additional Democratic seats.