Stung by scandal and rebelling against a state government known for its resistance to public scrutiny, South Dakota voters narrowly approved a ballot measure in November to impose ethics oversight and campaign finance restrictions aimed at cleaning up the capitol in Pierre.

But the state’s overwhelmingly Republican legislature is racing this week to set aside that new law by using its emergency powers, prompting cries of protest from voters and critics, who are calling the hasty efforts an antidemocratic power grab.

In effect, they say, the state’s voters are being told that their votes don’t matter.

“You have usurped the right of the people to make a decision that’s fully within their power,” Roxanne Weber, a software engineer from Pierre, told a state Senate committee on Wednesday, before the panel voted to send the plan to repeal the ethics package to the full Senate — a final step before it can go to the governor.

“Allow the people to have their voice,” Ms. Weber pleaded. “Allow them to give you suggestions. Allow them to be a part of the process.”