Democratic leaders such as House Speaker Nancy Pelosi of California say the change would spur the growth of renewable energy and green jobs. Environmental groups want Congress to act before a conference in December in Denmark, where world leaders will meet to craft an international climate-change agreement.
Opponents say the measure would send electricity and gas prices soaring and cost U.S. jobs.
Jack Gerard, president and CEO of the American Petroleum Institute, said his group helped organize at least 20 citizen rallies in recent weeks to air concerns about the climate-change plan.
"This issue is just below health care in terms of public anxiety," he said. "During this difficult economic time, there are lot of people who can't believe that Washington is going in a direction to add more costs to them."