WASHINGTON — Scott Pruitt, the administrator of the Environmental Protection Agency, told a Senate panel on Wednesday that one of his employees had worked without pay on her personal time to find him a place to live, a service that Democrats said amounted to a violation of federal law.

He also confirmed that he had established a legal defense fund to defray the costs of defending himself against 12 federal investigations into his spending and management decisions.

The acknowledgments came amid increasing allegations of legal and ethical misconduct by Mr. Pruitt that have led some lawmakers, including in his own party, to call for his resignation. They were part of testimony before the Senate Appropriations subcommittee on the environment, the third congressional hearing Mr. Pruitt has faced in less than a month.

While President Trump has said he continues to support his embattled E.P.A. chief, senior members of the White House staff have opened a renewed push to persuade their boss to fire Mr. Pruitt.