The Rev. T. Anthony Spearman, North Carolina’s NAACP president, speaks to a large crowd Jan. 10, 2017, about a federal court’s decision the day before striking down North Carolina's congressional map as unconstitutionally gerrymandered. (Julia Wall/AP)

Republican leaders in North Carolina pledged Wednesday to appeal a federal court's decision striking down their plan for redrawing congressional districts, promising to take to the Supreme Court a case that could have broad repercussions for future elections nationally.

A three-judge panel on Tuesday invalidated the map drawn by the Republican-controlled legislature in 2016, calling it improper partisan gerrymandering. The decision was the first striking down of a congressional map on the grounds that it was rigged in favor of a political party.

The court panel ordered lawmakers to redraw the boundaries by Jan. 29, although Republican leaders said Wednesday they plan to appeal the ruling to the U.S. Supreme Court; they said they also plan to request a stay of the ruling. They have a good chance at success, as the Supreme Court is often hesitant to become involved in a state's contests in an election year.

The decision still could reverberate widely, as lawmakers across the country are turning to technology to draw ever-more intricate maps aimed at controlling the outcome of elections. Already this term, the Supreme Court will consider challenges to gerrymandered maps in Wisconsin, where the legislature also is controlled by Republicans, and in Maryland, where it is controlled by Democrats.

The decision adds to a growing movement to have the Supreme Court finally decide whether partisan gerrymandering can be so extreme as to violate voters' constitutional rights. While the court has thrown out maps for other reasons, such as racial bias, it has never thrown out a state's redistricting plan on the grounds that it was too partisan. Such a ruling could radically change American elections.

Republican leaders said they would move swiftly to appeal to the Supreme Court. "We're absolutely going to file an appeal and we're absolutely going to request a stay," Rep. David Lewis, who chairs the House redistricting committee, said Wednesday. That process will start sometime this week, Lewis said.

Robin Hayes, chairman of the North Carolina GOP, defended the map, which looks more or less tidy — carefully drawn to avoid the irregular-shaped districts that have been a hallmark of gerrymandering.

"A 'gerrymander' is, by definition and common understanding, a strange-looking 'monster' drawing," he said in a statement. "This map is clearly not that."

He also took aim at the judge who authored the decision, James A. Wynn Jr., an appointee of President Barack Obama's.

"Judge Wynn is not being a judge, he is acting as a pundit by trying to impose his liberal beliefs instead of making a judicial ruling," Hayes said.

The panel's decision was in fact unanimous. Wynn was joined by U.S. District Judges W. Earl Britt, a Jimmy Carter appointee, and William L. Osteen Jr., a George W. Bush appointee. Osteen dissented on part of Wynn's rationale, however.

Tuesday's decision was made easier for the panel by a kind of smoking gun: Republican leaders in the North Carolina General Assembly openly conceded that the 2016 map was drawn to benefit Republicans.

They hired a consultant from the Republican National Committee to draw the map and excluded Democrats from the process, the court panel said. That consultant, the court said, testified that he was told "to minimize the number of districts in which Democrats would have an opportunity to elect a Democratic candidate."

"Rather than seeking to advance any democratic or constitutional interest," the panel wrote in a lengthy opinion, "the state legislator responsible for drawing the 2016 plan," Lewis, declared that he drew the map to advantage Republican candidates because he thinks "electing Republicans is better than electing Democrats."

The court's decision drew praise from some Democrats, who have been critical of Republican-led gerrymandering efforts. Those efforts have gained more attention because many state legislatures are controlled by the GOP.

"Today's ruling was just the latest example of the courts telling state legislators in North Carolina that citizens should be able to pick their representatives, instead of politicians picking their voters," Eric H. Holder Jr., attorney general under Obama and chairman of the National Democratic Redistricting Committee, said in a statement.

North Carolina has seen a cascade of redistricting challenges since a GOP takeover of the legislature in 2010. Last year, the Supreme Court ruled that North Carolina's Republican-controlled legislature relied on racial gerrymandering when drawing the state's congressional districts in 2013.

The decision gave a boost to dozens of protesters assembled across the street from the General Assembly on Wednesday morning to oppose a different redistricting effort — one that would redraw the state's judicial districts and put a constitutional amendment on this year's ballot to end judge elections, replacing them with a system that gives the legislature more influence.

Fred Barbash contributed to this report.