— The U.S. Supreme Court on Monday threw out a North Carolina court ruling that upheld Republican-drawn electoral districts for state and congressional lawmakers.

The justices ordered the state Supreme Court to consider anew whether the North Carolina legislature relied too heavily on race when it redrew voting districts following the 2010 census.

The high court issued a similar ruling last month involving a complaint from black Alabama Democrats that the Republican-dominated legislature illegally packed black voters into too few voting districts.

In Alabama, the justices said a lower court used the wrong test when it upheld legislative districts and determined that race was not the primary motivating factor in drawing boundary lines.

The Supreme Court said judges in North Carolina must revisit their ruling in light of the Alabama decision.

In both states, Republicans strengthened their grip on power through redistricting.

Sen. Bob Rucho, R-Mecklenburg, and Rep. David Lewis, R-Harnett, who led the redistricting effort, said they are confident the maps will pass muster on review.

“Since 2011, every court that has issued an opinion and the Obama Justice Department has reached the same conclusion – North Carolina’s redistricting maps are constitutional," Rucho and Lewis said in a joint statement. "Today’s procedural ruling is not unexpected, and we are confident that our state Supreme Court will once again arrive at the same result and the U.S. Supreme Court will affirm its decision.”

Election and civil rights advocacy groups and Democratic voters in North Carolina sued over the maps and argued that lawmakers created oddly shaped districts to create clusters of Democratic-leaning black voters. The redrawing of the map had the effect of benefiting Republicans elsewhere in the state. Republicans said the districts were lawful and designed to protect the state from legal claims under the federal Voting Rights Act.

“We have always known that the current maps were unconstitutional and are gratified that the Supreme Court of the United States has now set in motion a way forward for final disposition of this long-running and wrongly-decided case," Margaret Dickson, a former state House member who sued over the new districts, said in a statement. "The people of North Carolina deserve to have this resolved so that they can benefit from fair and legal maps for the 2016 elections.”

Bob Phillips, executive director of elections watchdog group Common Cause North Carolina, renewed the call for independent oversight of redistricting. A bipartisan group of lawmakers introduced a bill in February calling for such a change, but it has stalled in the General Assembly.

"Today's Supreme Court announcement shows once again that North Carolina's redistricting process is highly dysfunctional and in need of reform. Since 1980, our state's voting maps have been challenged in court more than three dozen times, leading to costly litigation and uncertainty for our elections. North Carolina deserves better," Phillips said in a statement.