Despite the defeat in the Senate last week of the Lieberman-Warner Bill, US legislation imposing binding emission caps look likely to be adopted next year after both Barack Obama and John McCain signalled they would have supported the proposed climate bill.

Neither presidential candidate cast votes on the Climate Security Act, but both said they would have voted in favour raising the prospect of the proposals being revived when the next president takes office in January 2009.

McCain had indicated previously that he would oppose the bill, citing inadequate incentives for nuclear power. However, he said in a statement that despite reservations he would have supported the bill. "I believe this legislation needs to be debated, amended, improved and ultimately enacted," he said. "That does not mean I believe the pending bill is perfect, and in fact, it is far from it."

The bill was defeated after 48 senators voted in favour and 36 against, leaving the bill 12 votes short of the 60 required to ensure it progressed. A further six Senators wrote letters indicating they would have voted in favour, had they been available.

Despite the defeat, supporters of the legislation hailed the move as a huge step forward in attempts to curb US emissions.

Democrat Senator Barbara Boxer, who helped shepherd the bill, said that the vote underlined changing US attitudes to global warming, noting that when climate change legislation was last voted on in 2005 it got only 38 votes. She added that supporters of the bill would now begin work on a "roadmap" for the next president that could see an amended version of the legislation adopted as early as next year.

Under the legislation, carbon emissions from 87 per cent of US power stations, oil refineries and other carbon intensive operations would have been included in a cap-and-trade scheme designed to cut US emissions by around 67 per cent by 2050.

Critics of the bill, including President Bush who said he would veto the legislation, argued that it would damage the US economy. But supporters of the bill, including the Ceres coalition institutional investors and a group of leading US energy firms, claimed the package of measures would help create jobs and provide the legislative framework for building a low carbon economy.

Environmentalists hailed the vote as a "turning point" in the US debate on global warming. Lexi Shultz, deputy director of the Climate Program at the Union of Concerned Scientists, said that the bill had gained such momentum that legislation capping emissions was now " inevitable".

"More senators than ever before supported moving forward on climate solutions, including senators who voiced opposition to global warming bills in the past," she said. "Americans are demanding global warming solutions. It's a shame they will have to wait another year. But our country will have another global warming debate in 2009 with a new Congress and president. Putting a cap on global warming pollution is inevitable."