Tom Wolf's campaign for governor has apologized and fired a consultant after acknowledging the aide lifted passages from a Wisconsin energy company's reports and reprinted them as part of Wolf's policy on energy efficiency.

"I have directed the staff to make sure nothing like this ever happens again, and have asked for a new process to be put in place to ensure it does not," Wolf said in a statement.

U.S. Rep. Allyson Y. Schwartz, one of his opponents in the Democratic primary, pointed out the "troubling plagiarism" Thursday, saying the episode raised doubts about the front-runner.

"At times of crisis, leaders take responsibility and don't pass the blame to their employees," Mark Bergman, spokesman for Schwartz's campaign, said Friday. "And yesterday, Tom Wolf failed the leadership test."

Wolf, a York businessman and former state revenue secretary, has led the primary for nearly two months on the strength of an overwhelming TV advertising presence. Rivals have been scrambling for ways to dent his image. Wolf's campaign said Friday that the attacks were desperation ploys.

Schwartz staffers identified four paragraphs in the Wolf document that included sentences identical to parts of two reports published by Johnson Controls, a Milwaukee-based international distributor of energy equipment. One describes the benefits of energy efficiency in reducing greenhouse gas emissions, and the others are about retrofitting existing buildings for efficiency.

Wolf's campaign said it collected ideas in its 46-page plan from public- and private-sector sources, as well as nonprofit think tanks and advocacy groups. Many are credited in footnotes.

"This was a mistake, and we regret it," spokesman Mark Nicastre said.