RALEIGH — A court-ordered redesign of North Carolina General Assembly districts would give Republicans a big and ingrained advantage to keep their veto-proof legislative majorities, a nonprofit legal watchdog group said Tuesday.

Based on past voting history, both the House and Senate maps released this weekend provide “a severe bias in favor of Republican voters” based on a social science measure of partisan tendencies that courts are beginning to accept in redistricting challenges, an attorney with the Washington, D.C.-based Campaign Legal Center said.

“If they go ahead with this plan, it will have a negative effect on Democratic voters and it will advantage Republican voters,” said Ruth Greenwood, who is one of the center’s attorneys already suing to overturn the GOP-led legislature’s design of congressional districts.

The Senate’s redistricting chief, Sen. Ralph Hise, called Greenwood’s analysis “a fallacy.” There’s no way to predict how voters shifted into new legislative districts might support candidates they’ve never previously had a reason to evaluate, he said in an interview.

While Republicans control both chambers and can draw the revised boundaries to their liking, the new legislative maps will be reviewed by a three-judge panel of federal judges.

Federal courts ruled the current maps, approved by the General Assembly in 2011, are unconstitutional because they diminished minority voting power. The existing maps also helped Republicans expand their legislative majorities and carry out their conservative agenda.

Republicans currently hold 74 of the 120 House seats and 35 of the 50 Senate seats. Not all districts had to be redrawn because of the 28 House and Senate districts found to have illegally weakened the political power of black voters.

Republican map-makers have said one of their goals in redrawing voting districts is protecting incumbents and considering how areas voted in the past while excluding the racial makeup of those living within those boundaries.

Meredith College political science professor David McLennan thinks the redesigned maps give Democrats a good chance of cutting GOP majorities, which are now so big lawmakers easily override Democrat Gov. Roy Cooper’s vetoes.

If Republican voter turnout next year is down and Democrats energized by opposition to President Donald Trump’s election get to the polls, Democrats could pick up enough House seats that Republicans can no longer ignore the threat of Cooper vetoing legislation, McLennan said. Still, Republicans are all but certain to keep control of both legislative chambers, he said.

Also Tuesday, legislators heard reactions to their redesigned maps from the public. Speakers were invited to sound off at a legislative office building in Raleigh or at community college campuses in Charlotte, Weldon, Fayetteville, Washington, Hudson and Jamestown.

Aylett Colston, 45, of Raleigh, came to tell lawmakers she objected to them drawing election districts to protect incumbents. That meant they were insulating themselves from having to respond to what voters wanted, she said.

“I think it’s clear that the public wants maps to be drawn that are impartial and respects the community and not be drawn for politicians’ own jobs security, which is what we have now,” Colston said.