Republicans blocked the bill, arguing that the government standards would have burdened businesses and done little to improve security.
Lieberman said the executive order would set up voluntary standards for critical systems. He said the president could also instruct regulatory agencies, such as the Federal Energy Regulatory Commission, to make the standards mandatory for the companies they regulate.
"Some of them will be forced to spend some more money than they otherwise are spending now to defend themselves, and us and their customers," Lieberman said. "But in the long run, this is the best thing we can do for our energy markets."