“This is one of the greatest coups we’ve seen in modern-day America,” said the House Democratic leader, Larry Hall. “This is an effort to nullify the clear vote of the people.”

Mr. Cooper said on Thursday that he might challenge the constitutionality of the measures in court, arguing that sweeping changes to the state’s power structure should not be rammed through without careful consideration and debate. If the Republicans succeed in stripping much of the governor’s authority, they will hamstring his ability to make sensible reforms in many areas, including public education, health care and environmental policy.

This legislative power grab is the latest underhanded step by a state Republican Party desperate to stay in power in a state where demographic changes would normally benefit Democrats. Republicans in North Carolina, a presidential battleground state, have used aggressive redistricting and voting suppression measures that are among the most brazen in the nation to win elections. The courts have blocked some of these efforts, but Republicans have found workarounds, for instance, by limiting voting hours and sites.

“I think they’re doing this because they think they can get away with it,” said Michael Gerhardt, a constitutional law professor at the University of North Carolina.

Even if Mr. Cooper was to succeed in beating back these efforts to weaken the governorship, he would assume power with Republican veto-proof majorities in the House and the Senate. That means his greatest asset, in the short run, will be the bully pulpit.