As many as 21 partners will be leaving Brobeck, Phleger & Harrison to set up a Clifford Chance office in San Francisco.

Clifford Chance’s 650 partners in all 28 offices completed a two-day vote Wednesday, agreeing to extend offers to former Brobeck chairman Tower Snow Jr. and 21 Brobeck partners, who immediately began submitting their resignations. By late Wednesday, those who had done so included James Burns Jr., who was firmwide managing partner until he stepped down in November, and Michael Torpey, head of the securities litigation practice group.