The British government proposed bold new environmental legislation Tuesday that would set legally binding, long-term limits on carbon emissions — a move it hopes will prompt the United States, China and India to follow suit.

The climate change bill would be the first legislation in an industrialized country to spell out such long-range goals, including a carbon budget set every five years that would cap CO2 levels and create an independent body to report on progress. The legislation also calls for binding targets as far ahead as 2050 for reducing carbon emissions.

"This is a revolutionary step in confronting the threat of climate change," Prime Minister Tony Blair said. "It sets an example to the rest of the world.

• Click here to visit FOXNews.com's Natural Science Center.

Britain's political parties have jostled in recent weeks for the "green" vote, seeking to display their environmental credentials in hopes of securing a key battleground in the next national election. Both Blair's Labour Party and the opposition Conservatives have seized on the issue — devoting more media time to the ozone layer than to British troops in Iraq.

Stung by bad news from Iraq, Blair's camp has worked to draw attention to issues in which he can seize the initiative — such as the environment. With Blair planning to step down by September, success in brokering a global carbon pact would be seen as a significant achievement.

Blair hopes Germany — which holds both the European Union and the Group of Eight presidencies — and Britain can lead work on a new global pact to curb emissions. The next step is getting the United States, China and India to make similar commitments, he said.

The bill must be approved by both houses of Parliament to become law. The government hopes it will be enacted in the first half of next year.

EU leaders agreed last week that the bloc will produce 20 percent of its power through renewable energy, as opposed to its current average of 6 percent.

Under the 1997 Kyoto Protocol, Britain is committed to reducing greenhouse gas emissions by 12.5 percent from 1990 levels by 2008-2012, as part of an overall European Union target of an 8 percent reduction. Some 10,000 power plants and other industrial facilities across the EU have been assigned quotas for maximum emissions, and can buy and sell allowances in an Europe-wide trading system.

Nations that ratified the Kyoto Protocol — the United States is not one — are expected in the next two years to negotiate post-2012 reduction targets.

In documents that accompany the draft bill, the British government said domestic action on climate change could change the terms of the debate.

The draft legislation was welcomed by environmentalists and opposition groups but some said the targets could be more ambitious.

The bill called for emissions to be reduced by 60 percent by 2050, and by as much as 32 percent by 2020. Targets were based on 1990 levels.

The Green Party said emissions should be reduced by 90 percent by 2050.

"Their insistence on mediocre — and dangerous — targets means all their efforts do not go nearly far enough," said Green Party spokeswoman Sian Berry.

Christian Aid said it should be increased to an 80 percent reduction by 2050. By 2020, the charity said, the goal should be a reduction of 40 percent.

London Mayor Ken Livingstone praised the legislation, but called for the government to address the issue of aviation emissions.

The opposition Conservative party, which has made the environment one of its key policy areas, prefers rolling targets instead of five-year goals.

John Coequyt, an energy policy specialist for Greenpeace USA, in Washington, said European initiatives on environmental issues were essential to pressure for a change in American policy.

"From the U.S. perspective, what we need more than anything is strong leadership out of the EU and U.K.," he said. "The more concrete goals the EU and U.K. set, the better."

But H. Sterling Burnett, a senior fellow at the National Center for Policy Analysis, a conservative Dallas think-tank, said he doubted there would be an immediate impact.

"It's hard to say they will lead the world anywhere, because the world is going to take a wait-and-see approach," Burnett said.