Pillsbury Winthrop Shaw Pittman Chair Mary Cranston announced Thursday that she will not run again after her third term ends in December. The firm’s managing partner, Marina Park, said she too is pondering her own future.

Cranston — the first female chair of a big national law firm, whose reign has spanned seven years and two mega-mergers — made the announcement a month after the firm posted a drop in 2005 profits per partner. But she said that had nothing to do with her decision.