A North Carolina lawmaker says she feels "rotten" after accidentally voting to override the veto of a bill to legalize fracking—the controversial technique of extracting natural gas—in the state.

Rep. Becky Carney, a Democrat from Mecklenburg, said she accidentally voted late Monday to override the governor's veto after asking fellow Democrats to uphold it. The House voted 72-47 against the veto—with Carney's vote clinching the number of votes needed for the override.

"It is late," Carney told WRAL-TV. "Here we are rushing to make these kind of decisions this time of night." The vote was called shortly before 11:30 p.m. ET.

"I feel rotten, and I feel tired," she continued. "And I feel that mistakes are made constantly when people are tired. But I take responsibility for my vote."

After realizing her error, Carney could be heard on the House floor saying, ""Oh, my God—it won't let me change my vote."

Under state law, lawmakers can change their vote if they make a mistake—unless their vote changes the outcome.

"There's a green button and a red button," House Speaker Thom Tillis told the News & Observer. "They should know which one to push."

Carney hit the green one. Then:

She panicked. She hit a different button to turn on her microphone and called to the House speaker on the dais. He didn't recognize her. So she rushed to the front, 20 steps from her seat in the eighth row down the red-carpeted middle aisle. Carney asked the clerk to check her vote. Green. Override. She then asked Tillis if she could change her vote. Tillis said House rules prevented it.

In May, Vermont became the first state to ban fracking, which critics say contaminates drinking water.

"Human beings survived for thousands and thousands of years without oil and without natural gas," Vermont Gov. Peter Shumlin said after signing the bill into law. "We have never known humanity or life on this plant to survive without clean water."

In the future, he said, "drinking water will be more valuable than oil or natural gas."