Senators Force Weaker Safeguards Against Cyberattacks

Strong opposition from Mr. McCain, Republican of Arizona, and others on behalf of the business community forced Democratic and Republican supporters of the legislation to drop provisions that would have given the federal government the power to enforce minimum standards on systems that run power plants, air traffic control systems, dams and similar facilities.

The Senate will debate the measure next week, even though the changes have raised new questions about its effectiveness.

“The key to successfully fighting this threat is not adding more bureaucrats or forcing industries to comply with government red tape,” Mr. McCain said Friday in a statement that announced that he and seven other Republican senators had introduced their own bill that calls for more information sharing among companies. “Instead, we must leverage the ingenuity and innovation of the private sector in partnership with the most effective elements of the federal government to address this emerging threat.”

Original versions of the bill, which was first drafted in 2009, called for giving the Department of Homeland Security the power to enforce minimum cybersecurity standards on infrastructure computer systems that, if damaged, would lead to mass casualties or economic loss.

But the U.S. Chamber of Commerce and other business lobbyists strongly objected, saying that such regulations would create a costly and cumbersome process.

The measure now before the Senate makes the minimum standards optional, dealing a significant setback to the administration, which had made legislation to safeguard computer systems a top national security priority this year. In April, the House passed its own version of the cybersecurity bill that encourages businesses and intelligence agencies to share information about attacks and threats to computer systems. Senate backers of the measure say their hope now is to pass the legislation and get into talks with the House. Even more attempts to change the Senate measure are expected.

James A. Lewis, a senior fellow at the Center for Strategic and International Studies and a cybersecurity expert, said the revised Senate measure did not provide any new powers to the federal government to protect computer systems of critical infrastructure.

“If it is passed, nobody will notice it,” he said. “You can do everything in the bill with an executive order.”

Dr. Lewis added: “The same way you wouldn’t say that we don’t need the F.A.A. because we can rely on incentives and a voluntary approach, we can’t rely on incentives and voluntary action for cybersecurity. Every day the risk gets bigger, it is not only countries but politically motivated individuals who can just download this stuff. A lot of us hoped Congress would have done better than this.”

Senator Joseph I. Lieberman, the independent from Connecticut who sponsored the measure as chairman of the Homeland Security and Governmental Affairs Committee, and the committee’s ranking member, Senator Susan Collins, Republican of Maine, said Friday that they were caught off guard by the determined opposition of Mr. McCain, who has for years made national security issues his priority.

“He knows that I’m disappointed,” Mr. Lieberman said, referring to Mr. McCain, one of his closest allies and friends in the Senate. “His natural side, based on his whole history, is to do the best thing for security and not to be worried about other factors.”

Tension between Mr. Lieberman and Mr. McCain bubbled to the surface on Wednesday at a closed-door meeting of senators and staff members about the legislation in the office of Senator Jon Kyl of Arizona, the No. 2 Senate Republican, said Congressional aides who attended the meeting and discussed the deliberations on the grounds that they would not be quoted by name.