The Washington lobbyist whose wife leased a Capitol Hill condominium to Environmental Protection Agency chief Scott Pruitt is leaving the firm where he has worked since 1983, citing the recent controversy for accelerating his departure.

J. Steven Hart, honorary chairman of Williams & Jensen, announced his resignation Friday in a letter to family and friends, a copy of which was reviewed by The Wall Street Journal. Mr. Pruitt paid $50 per night when he was using a condo owned in part by Vicki Hart, a health-care lobbyist. In total, Mr. Pruitt paid $6,100 for the lodging over about for six months last year, ending in July. He left in August.

“We had begun negotiating a severance agreement early this year,” Mr. Hart wrote in his letter. “Considering the last couple of weeks, I think it is easier on my family and the firm to expedite my departure.”

He will continue working, he wrote, with an independent legal practice and will be doing strategic business counseling for a few clients.

Mr. Hart gave up his chief executive title at the firm about two years ago.