A panel of federal judges on Tuesday declared Virginia’s congressional maps unconstitutional because they concentrate African American voters into a single district at the expense of their influence elsewhere.

The decision, handed down in the U.S. District Court for the Eastern District of Virginia, orders the Virginia General Assembly to draw up new congressional maps by April — potentially launching a frenzied and highly political battle for survival within Virginia’s congressional delegation.

The order delivered another victory for Democratic plaintiffs hoping to break up black-majority districts, which they say have been drawn by Republicans who have used the Voting Rights Act to dilute the influence of minority voters.

A similar case in Alabama in which Republicans prevailed will be heard by the Supreme Court this term.

“We’re obviously thrilled with the results,” said Marc Elias, a lawyer on the Virginia case who represented two voters from the district where the unconstitutional redistricting took place. “The Republicans engaged in impermissible racial gerrymandering in a cynical effort to gain seats. . . . We look forward to the state doing a new redistricting to comply with the court’s orders.”

Elias said that if Virginia does not appeal, its leaders will have to go “back to the drawing board” to draw their electoral boundaries.

Judge Robert E. Payne wrote in a dissenting option that incumbent protection — rather than race — motivated the redistricting, a practice which is legal.

The case can be appealed directly to the Supreme Court, an unusual legal quirk of the matter because it was decided by a three-judge panel, but whether that will happen remains unclear. Michael Kelly, a spokesman for Attorney General Mark R. Herring (D), said state lawyers were “reviewing the decision and assessing its impact and how best to move forward.” The attorney general’s office, in consultation with the Department of Elections, will decide whether to appeal, he said.

The court’s decision allows the current maps to remain in place for next month’s elections, and it focuses on the state’s lone black-majority district, the 3rd Congressional District, which stretches from Richmond to Hampton Roads and is now represented by Robert C. “Bobby” Scott (D).

But there was broad agreement Tuesday that, if the decision is not appealed, its impact could ripple across several districts in the state. Dave Wasserman of the Cook Political Report tweeted this on Tuesday: “Depending on how VA’s map is redrawn for 2016, the big loser here could be #VA04 Rep. Randy Forbes (R).”

Republican reaction to the ruling was muted; a spokesman for Virginia House Speaker William J. Howell (Stafford) declined to comment. But privately, some members of the GOP conceded that the redrawn map would probably make at least one and possibly several heavily GOP districts competitive for Democrats. If the state doesn’t appeal, the General Assembly would address the process when it reconvenes in January.

“There clearly would be at least a fourth district in Virginia where the Democrats would be more competitive than they are now,” said Bob Holsworth, a former Virginia Commonwealth University political scientist.

A legislative session that revolves around redistricting would likely heighten partisan rancor in the Capitol, where a bitter deadlock over Medicaid expansion between Republican lawmakers and Gov. Terry McAuliffe (D) threatened to trigger a government shutdown last summer.

“It’s pretty clear that the Republicans in the legislature and the governor are not on the best of terms these days, so the opportunity to redraw lines may be yet another example of the fact that gridlock rules the roost in Richmond,” said Stephen J. Farnsworth, director of the Center for Leadership and Media Studies at the University of Mary Washington.

Yet Republicans and Democrats would be taking a big risk if they did not find a way to come to an agreement. If the GOP-

controlled legislature did not pass a plan that McAuliffe would be willing to sign, more uncertainty could ensue: A veto from McAuliffe would send the map to the courts for the judges to redraw.

McAuliffe said in a statement, “Today’s ruling demonstrates the need to get partisan politics out of how Virginia draws its legislative boundaries.”

Earlier this year, the Supreme Court agreed to hear a similar challenge to Alabama’s legislative reapportionment plan. In that case, the challengers said Republicans altered districts that were already drawn to give minority voters significant influence to include even more black voters, raising the proportions in at least one district to more than 70 percent.

Both cases came on the heels of a 2013 Supreme Court decision invalidating a key provision of the Voting Rights Act that required some states with a history of discrimination to not draw districts in such a way that created a “retrogression” in minorities’ ability to elect their preferred candidates. That generally meant not breaking up majority-black districts.

Although the Voting Rights Act was meant in part to ensure elected representation for minorities, Democrats have argued in recent years that Republicans have used the act and its provisions to justify diminishing black — and Democratic — influence outside of the majority-minority districts.

Such arguments have sometimes created tensions between minority groups and the Democrats they most often favor. Black incumbents especially want to make sure that districts remain safe for reelection, while other Democrats want minority voters more dispersed to increase the party’s chances of winning more races.

Scott, who is running unopposed this fall, issued a statement noting that he was not involved in the suit but that he backed another map during redistricting in 2011. He first won election in 1992, after Virginia, under a directive from the Justice Department, created the majority-black district.

“I was a strong proponent of the redistricting plan sponsored by State Sen. Mamie Locke, which made all congressional districts in the Commonwealth more compact and contiguous,” Scott said. “I hope and expect the General Assembly will more equitably and appropriately balance the influence of all Virginia’s voters, as mandated by this decision, when they redraw the third congressional district and adjacent congressional districts next session.”

The judges who decided the Virginia case mentioned the Supreme Court decision on the Voting Rights Act in their opinion, but legal experts said it was largely irrelevant to what they ultimately found: that the state’s recent redistricting map was unconstitutional because race was the predominant factor in drawing the boundaries of the 3rd District.

Under the map, which was drawn in 2012, the district went from a voting-age population that was 53.1 percent African American to one that was 56.3 percent African American.

“In today’s case, the challenger said, ‘you’ve violated this rule against unconstitutional racial gerrymanders, because . . . you’ve packed in these African American voters into this 3rd Congressional District, and you didn’t have a good reason to do so,’” said Richard Hasen, a University of California at Irvine law professor who specializes in election law.

Jon Greenbaum, the chief counsel for the Lawyers’ Committee for Civil Rights Under Law, said the judges looked in particular at how the map split cities and shaped the 3rd District, making it an “outlier” compared with others. He said the state will probably maintain an African American majority in the district if it is redrawn — as another portion of the Voting Rights Act indicates it should — but that majority will not be as sizable.

“What we would hope Virginia would do would be to create a plan that maintained the district as a black-voting-age-majority district and cured the fault of this plan,” he said.

Jenna Portnoy contributed to this report.