The Senate could leave town this week for a month long break without passing legislation to protect the U.S. electrical grid, water supplies and other critical industries from cyber attack and electronic espionage. Sponsors of the bill scrambled Wednesday to overcome Republican resistance to the measure, but they appeared short of the votes needed for passage despite dire warnings from top national security officials about the potential for devastating assaults on the computer networks that control the country's essential infrastructure. President Barack Obama is urging lawmakers to pass the legislation. The principal stumbling block on Capitol Hill is what role the government should play in protecting U.S. businesses from cyber attacks. Republicans have argued the bill would lead to mandatory rules that would increase the private sector's costs without substantially reducing the risks.