Crowell & Moring, which has called for President Donald Trump’s immediate removal from office, said late Friday that 18 law firms have joined the firm in urging Vice President Mike Pence to invoke the 25th Amendment.

Crowell said the firm and others, which include four other Am Law 200 firms as well as midsize and smaller practices, sent a joint letter to Pence on Friday evening. The letter said the firms’ attorneys had “watched in horror as the U.S. Congress was subject to a mob’s raid and occupation of the Capitol” that interrupted the orderly transition of power.