The White House and other Senate Democrats argue the cybersecurity mandates are necessary to protect critical systems, but many Republicans say they would be an unnecessary burden on businesses.
In his letter to Dave McCurdy, the head of the American Gas Association, Rockefeller questioned whether gas companies passed up opportunities to better secure their systems because of the cost.
"I fear that the business justification for securing critical infrastructure will not come until it is too late, after a cyber attack does great damage to our economy, or worse, causes a mass casualty event," Rockefeller wrote.
McCurdy, a former Democratic lawmaker from Oklahoma who chaired the House Intelligence Committee, said he recognizes the "gravity of our nation’s cyber vulnerabilities."
"We are consistently working to improve the safety and security of our systems," he said in a statement.
—This story was updated at 5:05 p.m. with a statement from Dave McCurdy