RALEIGH, N.C. (AP) — Yet another redistricting lawsuit has been filed in North Carolina, this one challenging General Assembly boundaries that Democrats and election reform advocates say remain illegally tainted by excessive favoritism toward Republicans.

Common Cause North Carolina, the state Democratic Party and more than 20 Democratic and unaffiliated voters sued GOP mapmakers Tuesday in Wake County court. They allege the lines are illegal partisan gerrymanders that make it virtually impossible for Democrats to win majorities in the House or Senate.

The plaintiffs want maps last drawn in 2017 — in response to previous litigation — struck down for violating the North Carolina Constitution. They also call for new boundaries to be approved for the 2020 elections, which kick off in less than 13 months with candidate filing. A three-judge panel would hear the matter, followed by a likely appeal to the state Supreme Court.

“We’re here to say enough is enough. Partisan gerrymandering must end now,” Common Cause NC Executive Director Bob Phillips said at a news conference. “It rigs elections and it’s wrong no matter which party does the deed.”

The political stakes are great in North Carolina, a presidential battleground state in which Republicans have controlled state government for much of this decade. Barring a new method to draw districts, whichever party wins each legislative chamber in 2020 will get to draw the maps for the next decade. The governor — currently Democrat Roy Cooper — doesn’t have veto power in redistricting.

Still, the lawsuit comes a week after Democrats actually won at least 11 additional legislative seats, with most of those victories originating in districts they identified as being wrongly packed or diluted with Democratic voters.

While Democrats did end the GOP’s veto-proof control in the legislature, they say they’re being robbed of more seats. According to the litigation, Democratic legislative candidates won about 51 percent of the overall votes cast in their elections but they are expected to win only 44 percent of the General Assembly seats when results are finalized.

State GOP Executive Director Dallas Woodhouse quipped: “Only North Carolina Democrats would file a lawsuit to overturn districts that they just won.”

Lawyers for the plaintiffs say just because Democrats had a better year doesn’t undermine their arguments that it’s unlawful to sort voters into districts chiefly to create desired political outcomes. Republicans “discriminated against Democratic voters on the basis of their political beliefs and their prior votes,” said Stanton Jones, a Washington-based attorney.

At least eight lawsuits have been filed challenging North Carolina maps on the basis of racial and partisan bias since the current round of redistricting began in 2011. The lawsuits resulted in the redrawing of congressional lines in 2016 and legislative districts in 2017 — both to address determined racial bias. The state has spent millions of taxpayer dollars defending the maps.

Legal fees for Tuesday’s lawsuit are being paid in part by an arm of the National Democratic Redistricting Committee, which is led by former Obama administration Attorney General Eric Holder with a goal of more favorable maps for the party in the 2020s. Holder this fall endorsed state Supreme Court candidate Anita Earls, who as a lawyer represented some who sued over maps earlier this decade. Earls won, so next year five of the seven justices will be registered Democrats.

The office of Republican Senate leader Phil Berger, who is one of the defendants, mentioned Earls in a statement, saying she should recuse herself if the case reaches the court because of her redistricting work history. Otherwise, Berger spokesman Pat Ryan said, the lawsuit “is a corrupt attempt at judicial gerrymandering, hoping the liberal state court will rewrite the constitution and draw maps favorable to Democrats.”

Partisan gerrymandering claims against state legislative lines are similar to those Common Cause and the Democratic Party filed two years ago in federal court over state congressional districts. Federal judges have twice ruled the congressional map violated protections for Democratic voters. The U.S. Supreme Court, which has never declared district maps anywhere as partisan gerrymanders, is considering whether to hear an appeal in that case.

By targeting the North Carolina Constitution in Tuesday’s lawsuit, the result won’t be dependent on what the U.S. justices decide. It alleges the GOP maps violate the state constitution’s provisions protecting freedom of speech and ensuring people are protected by laws equally and that elections are “free.”

Under the partisan gerrymandering claims, those who sued contend GOP legislators used political and election data to manipulate the lines of about 75 House and 20 Senate districts so that Republicans and their candidates won more seats at the expense of Democrats and the voters who support them.

“What gerrymandering does is it makes for lazy politics,” said Virginia Brien of Charlotte, an unaffiliated voter and plaintiff. “It makes for people not having to engage with citizens who have different ideas about how to get something done.”