In the waning days of North Carolina’s legislative session last year, the Republican majority tucked an unexpected measure into a bill that was nominally dedicated to storm relief. It gave the state auditor, who typically serves as a fiscal watchdog, the job of appointing the state elections board, which North Carolina governors had been responsible for since 1901.

Critics of the bill viewed it as a blatant power grab, given that the newly elected auditor was a Republican and the incoming governor, Josh Stein, a Democrat.

The law took effect on Thursday, making North Carolina the only state to give its auditor, Dave Boliek, power over an elections board. Mr. Boliek promptly nominated three Republicans to the five-member board, which previously had a Democratic majority.

The change could be instrumental in deciding who wins a protracted legal battle over a North Carolina Supreme Court seat. The case has received national attention because of the Republican challenger’s quest to throw out thousands of votes in an attempt to reverse his election loss. A Republican-controlled elections board could interpret court rulings more favorably for the challenger, raising the chances of the election being overturned.

The law was further evidence of the bar-fight nature of politics in the state, where the Republican-controlled legislature has recently passed laws stripping power from Democratic officials, and where both parties have engaged in gerrymandering over the decades.

“I think what all this says is that brass-knuckle politics is here to stay in North Carolina — that purple-state status doesn’t lead to purple politics, but rather brass-knuckle politics,” said Chris Cooper, a political science professor at Western Carolina University in Cullowhee, N.C.