"Legislation that focuses exclusively on facilitation of information sharing … jeopardizes the foundation of cybersecurity by improperly pitting human rights against security," the letter reads. "We urge you to pledge to veto CISA and all future legislation that takes a similar approach."

In a letter sent to Obama on Tuesday, Access, the Electronic Frontier Foundation, Reddit, and dozens of other privacy and Internet freedom groups urged the president to publicly oppose the Cybersecurity Information Sharing Act, which would make it easier for companies and the government to share sensitive data with one another about cyberattacks.

It hasn't passed Congress yet, but privacy groups are already asking President Obama to pledge to veto a controversial cybersecurity bill they fear would bolster the National Security Agency's spying powers.

The letter comes just a week after the Senate Intelligence Committee cleared the legislation 12-3 during a closed-door vote. Sen. Dianne Feinstein, the panel's chairwoman, said the measure will help retailers and others protect the personal information of customers and help thwart hacking attempts by foreign governments.

CISA would make it possible for businesses and government agencies to swap data about potential hackers and security flaws in order to learn best practices for defending against such malicious activity.

But a familiar chorus of privacy and Internet freedom groups have risen up in opposition to the bill, which they say is too similar to the Cyber Intelligence Sharing and Protection Act that the House passed last year. That passage came despite Obama saying he would veto the measure for lacking appropriate safeguards on privacy and confidentiality.

Some of the Senate bill's language seeks to protect privacy by requiring companies that share information to first remove personally identifiable data (e.g. names or Social Security numbers) of Americans.

Those offerings have not assuaged concerns of privacy advocates, however, who argue the legislation would make it easier for a company like Facebook to turn over vast quantities of private online data to the government. Skeptics say information given to the Homeland Security Department would be also delivered to the NSA and other intelligence agencies.

In addition, the letter maintains that immunity protections for companies limit their interest in protecting customer data and do not require personal information to be stripped out before data is shared with the government unless there is verifiable knowledge that such information is present.

"While amendments attached to CISA during the committee markup alleviate concerns about the bill's disproportionate impact on non-U.S. persons, the revised bill fails to correct many of the bill's most basic problems," the letter states. "In fact, while amendments ostensibly require additional limited data use and retention limitations, 11 of those provisions are left wide open to secret government interpretation."

Critics of government surveillance have long argued that intelligence agencies operate under loose interpretations of vague statutes to collect far more data on Americans than Congress intended to allow.

It is unclear when the full Senate may consider CISA, but some aides have said its backers may attempt a vote before the August recess.