Over resounding opposition from tech giants like Apple and Twitter, as well as a significant grassroots opposition campaign, the Senate on Wednesday proceeded with debate over the Cybersecurity Information Sharing Act (CISA).

CISA aims to facilitate information sharing regarding cyberthreats between the government and the private sector, but the technology sector and consumers alike have expressed privacy concerns.

Twitter's policy public policy team weighed in earlier in the week:

Security+privacy are both priorities for us and therefore we can't support #CISA as written. We hope to see positive changes going forward. — Policy (@policy) October 20, 2015

In spite of the major opposition to the bill, both Republican and Democratic leaders support it in the Senate. The Obama administration supports it, and the House has already passed similar legislation.

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Senate Majority Leader Mitch McConnell, R-Kentucky, defended the bill on the Senate floor Wednesday, arguing that "cybersecurity experts" have endorsed the "modern tools" the bill implements and that it "contains important measures to protect individual privacy."

Senate Minority Leader Harry Reid, D-Nevada, gave a half-hearted endorsement of the legislation: "The bill, which is okay, is better than nothing - let's put it that way," he said on the Senate floor Wednesday. It "addresses a serious national security issue," he added.

The bill gained more traction after the massive hack in which the records of nearly 22 million people were stolen from government computers.

"The ability to easily and quickly share cyber attack information, along with ways to counter attacks, is a key method to stop them from happening in the first place," Sen. Dianne Feinstein, D-California, a CISA sponsor, said in a statement after the hack.

She and Senate Intelligence Committee Chairman Richard Burr, R-North Carolina, have emphasized that the bill does not require companies to send customers' private information to the government. "The cyber threat information sharing is completely voluntary," they wrote in a fact sheet.

Several major industry leaders and associations, however, are not satisfied.

"We don't support the current CISA proposal," Apple said in a statement Tuesday, the Washington Post reported. "The trust of our customers means everything to us and we don't believe security should come at the expense of their privacy."

Last week, the Computer & Communications Industry Association, a group that represents Google, Facebook, Yahoo, Amazon, Sprint and others, said the bill "does not sufficiently protect users' privacy or appropriately limit the permissible uses of information shared with the government."

Earlier in the year, dozens of cybersecurity academics and civil society organizations sent a letter to Congress expressing their concern that CISA would threaten civil liberties without improving cybersecurity. On top of that, activists worried about online privacy turned to some old-school technology -- sending Congress more than 6.2 million faxes -- to express the opposition to the bill.

The activist group Fight for the Future this week activated its Internet Defense League against CISA, rallying more than 15,000 websites to alert its users to the threats of the bill.