Facebook, Google, Microsoft and other top technology companies are warning the Senate not to follow the House’s lead with a compromised plan to reform the National Security Agency.

A coalition of nine major companies is planning to publish an open letter calling for the Senate to limit the NSA’s powers on Thursday, the one-year anniversary of Edward Snowden’s first revelations about the spy agency.

The same day, a top trade group head will warn the Senate Intelligence Committee that the spy agency’s activities could lead to “seriously damaging long-term implications” for the global economy.

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Together, the efforts amount to a concerted push to pressure the Senate to rein in surveillance, after the House passed a bill that many reformers thought was too weak.

“Over the last year many of our companies have taken important steps, including further strengthening the security of our services and taking action to increase transparency,” the nine-member Reform Government Surveillance coalition wrote in the letter, which will be published in The Washington Post, New York Times and Politico. “But the government needs to do more.”

The version of the USA Freedom Act passed by the House last month “could permit bulk collection of Internet ‘metadata’ ” and would prevent the companies from providing “even greater detail” about the government requests they received, the group added.

The tech coalition is made up of Google, Facebook, AOL, Microsoft, Apple, Twitter, Yahoo, Dropbox and LinkedIn.

In prepared testimony ahead of Thursday’s Senate Intelligence hearing, Information Technology Industry Council President Dean Garfield warned lawmakers that the House-passed bill “may not fully achieve” the goal of ending bulk data collection, as its backers claim.

The trade group includes major companies like Dell, Sony, Intel and eBay, in addition to several of the companies in the Reform Government Surveillance group.

Tech companies say that the disclosures from Snowden have caused consumers around the globe to grow distrustful of their services.

Civil liberties advocates and Web firms had originally backed the USA Freedom Act as a way to make sweeping changes to the NSA, but compromise measures in the days before it headed to the House floor caused many of them to pull their support. When it passed last month, dozens of original sponsors ended up voting against it.