The US Senate has rejected efforts to curb carbon dioxide emissions from industrial power plants.
Senators voted 55-43 against the an amendment to the bill on abrupt climate change, which would have required power stations and factories to reduce their emissions to 2000 levels by 2010.
Many scientists have identified greenhouse gas emissions as a major source of global warming.
The measure was opposed by the Bush administration, which said it would seriously damage the US economy.
The amendment was co-sponsored by Republican John McCain and Democrat Joe Lieberman.
Senator McCain told the Senate that it was "a very minimal proposal" that should be the first step.
"We have to start somewhere," he said, showing photographs taken from outer space that depict a melting Arctic ice cap.
"We will be back, because these pictures will continue to get worse and won't improve until we begin to address this issue."
However, opponents of the bill backed the White House view that it would increase household energy bills and hamper job creation.
President George W Bush provoked widespread international criticism in 2001 by rejecting the Kyoto Protocol on tackling climate change, which would also have committed the US to cutting greenhouse gas emissions.
In its place, Mr Bush has proposed a voluntary plan for curbing the gases.