Tens of millions of dollars are pouring into both sides of Virginia’s high-stakes redistricting fight, a closely watched test in the national battle over gerrymandering that could help determine control of Congress in November.

On Tuesday, Virginia voters will decide whether to approve a constitutional amendment that would allow the state legislature to redraw congressional districts ahead of the 2026 elections, temporarily overriding the state’s bipartisan redistricting process until after the 2030 census. The referendum follows President Donald Trump’s push last year for mid-decade map changes in Republican-led states.

The vast majority of the money pouring into the race in Virginia—around 95% of the almost $100 million raised—has come from tax-exempt nonprofits, also known as 501(c)(4) organizations, which are not required to report their donations. These organizations are a major source of so-called dark money in political campaigns, allowing large sums to be spent without public disclosure of donors.

Despite the roughly 15-point margin which won Democratic Gov. Abigail Spanberger her office in 2025, Tuesday's vote is expected to be a much narrower fight. Recent polls from Quantus Insights and the Washington Post suggest only a slim majority in favor of a redraw.

The “yes” side is funded primarily by the Virginians for Fair Elections referendum committee, which has received $64 million in contributions between December 2025 and April from these nonprofit organizations. All figures are based on campaign finance records reviewed by TIME.

The political nonprofit arm of House Democrats, House Majority Forward, which is not required to disclose its donors, accounted for almost $40 million of those donations. 

Campaign finance records show that conservative nonprofit Per Aspera Policy Inc. was the largest donor to Justice for Democracy, which targeted Black Virginia voters with anti-redistricting mailers that likened the referendum to Jim Crow-era voter suppression. 

Per Aspera’s designation as a nonprofit allows it to keep its donors secret, but Thiel’s history with the group and its tactics has drawn scrutiny. Thiel previously gave a six-figure donation to Per Aspera as it was funding ads in Kris Kobach’s failed bid for Kansas governor, according to The Kansas City Star.

The Virginia mailers have received criticism from the National Association for the Advancement of Colored People (NAACP), who called them “manipulative” and “racist”, as well as from Black leaders in the state, including Virginia Attorney General Jay Jones.

“Peter Thiel, one of Donald Trump’s top billionaire backers, is spending millions in Virginia to push a campaign built on lies and racial division,” Jones said. “These ads deliberately exploit the history of Jim Crow and the Civil Rights Movement to mislead Black voters and suppress participation.”

The fight in Virginia is one of the Democrats’ last major opportunities to gain ground in the broader gerrymandering race, one that former Attorney General Eric Holder has described as a “national fight.”

“It's not a fight only about Virginia,” Holder said on Sunday on CBS News’ Face the Nation.

Last June, President Trump called on Texas to start a congressional redistricting process mid-decade—rather than after the next census in 2030. The unusual move triggered similar efforts in other Republican-controlled states, including Ohio, North Carolina and Missouri.

“And so the question I have for people who are critical of what we're doing, is: what were we supposed to do? Nothing? Just allow them to try to stack the deck, to try to steal seats,” Holder said. “All we're trying to do is meet them and try to make the system as fair as it possibly can be.”

Last year, Democrats secured a key victory in California, where voters approved new maps aimed at gaining as many as five seats in the midterm elections.

With the 2026 midterms approaching, Virginia would be a huge prize for Democrats attempting to take the House. While the state currently hosts a majority of six Democrats to five Republicans, passing Tuesday’s referendum could lead to a map with a 10-1 advantage.

Beyond the influx of so-called dark money, the referendum has garnered attention from national political figures, including Trump, California Gov. Gavin Newsom, Texas Sen. Ted Cruz, and former President Barack Obama. 

“Over the past year, several Republican-controlled states have taken the unprecedented step of redrawing their congressional maps in the middle of the decade, and they’ve done it for a simple reason—to give themselves an unfair advantage in the midterms this fall,” Obama said in a video last month. “In April, Virginians can respond by making sure your voting power is not diminished by what Republicans are doing in other states. This amendment gives you the power to level the playing field in the midterms this fall.” 

Republicans, including Speaker Mike Johnson and former Gov. Glenn Youngkin, have spent the last month participating in rallies funded by Virginians for Fair Maps, trying to convince Virginia voters that the referendum is unfair.

“Virginia is under assault because we have leadership in Richmond that is trying to take away your vote,” Youngkin said at a rally in Lynchburg in early April.