The US Senate has narrowly rejected a plan to allow oil drilling in an Alaskan wildlife refuge.
The defeat is a major setback for President George Bush's administration, which had insisted that oil exploration in the 19 million acre (7.7 million hectare) Arctic National Wildlife Refuge would help safeguard America's supply of energy.
Alaskan oil has been an important part of George Bush's energy plan
Despite intense lobbying by the White House, an amendment was passed on Wednesday by 52 votes to 48 removing the provision allowing drilling to commence from the 2004 budget resolution.
The vote was split largely down party lines.
Most Republicans were keen to start oil exploration in the area, in order to reduce the country's dependence on fuel imports.
But Democrats, a few moderate Republicans and environmental groups argued that the Arctic wilderness should be left untouched, and oil exploration concentrated elsewhere.
Utilisation of the oil beneath the coastal plains in north-eastern Alaska has long been a key part of President Bush's energy plan.
"It's unfortunate that the Senate missed an opportunity to increase America's energy independence at a critical time," said White House spokeswoman Claire Buchan after the vote.
The solution to our long-term energy problems is not to
just open this environmentally sensitive area to drilling
Democrat Senator Jeff Bingaman
With war starting against Iraq, proponents of the Alaskan drilling plan stressed that any oil found in the area would help the US reduce its reliance on precarious foreign supplies.
"Of course we are disappointed, at a time when our economic security, our national security are at stake," said Senator Kay Bailey Hutchison, a Texas Republican.
But those against the plan said drilling in the area would not significantly reduce America's dependence on imported oil.
"The solution to our long-term energy problems is not to just open this environmentally sensitive area to drilling," Democrat Senator Jeff Bingaman said during the Senate debate.
Environmentalists insisted that oil exploration in the refuge would disturb polar bears, affect calving grounds for caribou and alter the patterns of millions of migratory birds that fly to the area each summer.
"The environmental degradation that we've witnessed for two years ended today," said triumphant Democratic Senator Dick Durbin after the result.