The heavyweights of Silicon Valley are pushing for government surveillance reform.

Google (GOOGL), Facebook (FB), Amazon (AMZN) and Microsoft (MSFT) were among two dozen tech companies to sign a letter Friday calling on Congress to overhaul a controversial foreign surveillance program.

The program, Section 702 of the Foreign Intelligence Surveillance Act, served as the legal basis for the NSA to track emails and phone calls of non-U.S. citizens -- while potentially ingesting communications from Americans as well.

It first gained attention after the revelations of NSA whistleblower Edward Snowden in 2013. Congress is in the process of weighing reforms for the program. It must vote to renew Section 702 before the end of the year, otherwise it will expire.

The letter, addressed to the chairman of the House Judiciary Committee, asks Congress to consider several reforms to the program to ensure greater transparency and privacy protections.

Related: Silicon Valley's impossible balancing act with Trump

Any renewal of the program, according to the letter, should "reduce the likelihood of collecting information" about foreigners "who are not suspected of wrongdoing." It should also "require judicial oversight" for reviewing communications of U.S. citizens.

Ed Black, president and CEO of CCIA, a technology trade group that signed on to the letter, said in a statement the deadline to renew makes it "the right time to question" the program's balance between national security and "protecting individual rights."

The push has the potential to create yet another clash between the tech industry and President Trump. The Trump administration reportedly supports a "clean reauthorization" of the FISA law.

The tech industry has already entered into legal battles with the new administration over the travel ban and transgender protections. More recently, tech companies have begun to prepare for a fight over net neutrality.

Neema Singh Guliani, legislative counsel at the ACLU, says there hasn't been a "clear position statement" from the administration on this issue yet. Like the tech companies, the ACLU has called for substantial reforms to the program -- or else to let it die.

"There are procedures in place that allow for warrantless collection of American's communications in ways that I think most people find very troubling," she said. "If Congress is not going to undertake that [reform], they should allow the law to sunset."