The Virginia Supreme Court on Monday will hear arguments in a Republican challenge to the redrawn congressional map that was approved by voters last week and could net Democrats four additional U.S. House seats.

The case contends that the Democratic-led General Assembly violated procedural requirements by placing the constitutional amendment before voters to authorize mid-decade redistricting. If the court agrees that lawmakers broke the rules, it could invalidate the amendment and render last week’s statewide vote meaningless.

The Virginia court proceedings mark the latest twist in a national redistricting battle between Republicans and Democrats seeking an advantage in a November election that will determine whether Republicans maintain their narrow majority in the U.S. House.

President Donald Trump urged Texas Republicans to redraw districts to their favor last year in an attempt to win several additional House seats. That set off a chain reaction of similar moves in other states, leading to the voter approval last week of Virginia’s new map.

Next up is Florida, where Republican Gov. Ron DeSantis has included congressional redistricting on the agenda for a special session of the GOP-controlled Legislature beginning Tuesday.

On Sunday, Trump said he was in favor of the Florida attempt and criticized the Virginia amendment that was pushed by Democrats.

“It’s a very bad thing for our country. Very, very bad,” he told Fox News Channel’s “The Sunday Briefing.”

So far, the two major parties have battled to a near draw. Republicans think they could win up to nine more seats under revised districts in Texas, Missouri, North Carolina and Ohio. Democrats think they could win as many as 10 additional seats under new districts in California, Utah and Virginia. But legal challenges remain in both Virginia and Missouri.

Virginia currently is represented in the U.S. House by six Democrats and five Republicans who were elected from districts imposed by a court after a bipartisan redistricting commission failed to agree on a map after the 2020 census. The new districts, which narrowly won voter approval last Tuesday, could give Democrats an improved chance to win 10 districts.

At issue before the state Supreme Court is whether those districts should be invalidated because of the process used by lawmakers.

Because the state’s redistricting commission was established by a voter-approved constitutional amendment, lawmakers had to propose a new constitutional amendment to redraw districts themselves. That required approval of a resolution in two separate legislative sessions, with a state election sandwiched in between, to place an amendment on the ballot.

In January, a judge in rural Tazewell County, in southwestern Virginia, ruled that lawmakers failed to follow their own rules for adding the redistricting amendment to a special session last fall. Circuit Judge Jack Hurley Jr. also ruled that lawmakers failed to initially approve the amendment before the public began voting in last year’s general election and that the state had failed to publish the amendment three months before the election, as required by law. As a result, he said, the amendment is invalid and void.

The Virginia Supreme Court placed Hurley’s order on hold and allowed the redistricting vote to proceed before hearing arguments on the case. Republicans have filed at least two additional legal challenges, which also are winding their way through the courts.