Nearly two dozen Patton Boggs partners will leave the firm in the coming months, while those who intend to stay have pledged allegiance to management as they tackle a possible merger and continue to revamp the Washington-based law and lobbying brand.

Edward Newberry, Patton Boggs managing partner, said Friday that his firm would survive—healthy and profitable. The firm faces a new round of 15 to 20 forced reductions in the partnership and a handful of defections.