The companies originally planned to file the brief later this coming week, but accelerated efforts over the weekend after other legal challenges to the order, according to people familiar with the matter.
Other companies involved include firms in finance, manufacturing, energy and consumer goods sectors. Its not clear yet which companies will agree to sign on. The goal is to publish the open letter this week.
More than any other industry, the tech enclave embraces the work and aspirations of immigrants. At least half of the top 20 U.S. tech companies were founded or are currently led by someone who came from another country.