The proposal by Senator Richard Lugar would delay standards on coal plants and stop short of the "cap-and-trade" system requiring emission curbs -- a signature part of European efforts and a Democratic-led bill backed by President Barack Obama.

Instead, the bill would focus on cutting US dependence on foreign oil by supporting domestic production, renewable energy and vehicle efficiency -- though not offshore drilling, in light of outrage over the BP spill.

Lugar, whose state of Indiana is a major producer of emission-heavy coal, said Democratic calls for a cap-and-trade system "represent a significant disconnect with the priorities of many Americans."

He warned of a backlash by Americans against climate efforts if Congress imposes "an expensive cap-and-trade plan by a narrow political margin at a time when the added expense could intensify economic pressures."

Many Republicans have made cap-and-trade an issue this election year, saying it would put the economy at risk and casting doubt on science that warns of worsening disasters and the extinction of species unless action is taken.

Lugar cast his bill as a compromise and was joined by a fellow moderate Republican senator, Lindsey Graham, who earlier worked with Democratic Senator John Kerry on his bill unveiled last month but then called it unrealistic.

Graham said he believed that global warming was real but that his primary concerns were creating jobs and reducing dependence on oil bought from "regimes that don't like us very much."

"America is more dependent on foreign oil today than we were before 9/11," Graham told a news conference with Lugar. "For me, to continue that practice is a national security nightmare."

"The job creation of the 21st century, I believe, will be built around a low-carbon economy," Graham said. "It's either going to happen here, China or in India. I'd rather it happen here."

The bill aims to reduce greenhouse gas emissions by at least 20 percent by 2030 compared with a scenario if the United States did nothing.

It is less ambitious than a bill approved by the House last year and the proposal by Kerry and independent Senator Joe Lieberman. Both would cut emissions by 17 percent by 2020 from 2005 levels.

The Kerry bill already falls well below the UN climate change panel's recommendation of cuts of 25 to 40 percent from 1990 levels.

Kerry and Obama argue that putting a price on carbon would unleash a new green economy, providing a valuable source of high-paying jobs which other countries are already creating.

The American Lung Association voiced "outrage" over the Lugar bill, warning it would harm public health by letting coal plants avoid new environmental standards if they promise to shut down by the end of 2018.

Daniel Weiss, a climate expert at the left-leaning Center for American Progress Action Fund, said that Lugar was proposing no actions to curb emissions that Obama was not planning anyway.

"This bill is a fig leaf for people who make it want to seem like they're doing something," Weiss said.

While the Senate has yet to vote on any comprehensive climate bill, it is expected on Thursday to vote on a related measure led by Republicans that would bar the Environmental Protection Agency from regulating carbon emissions.

Ahead of December's Copenhagen climate summit, the Obama administration threatened that the agency would regulate emissions if Congress does not approve legislation on its own.

The White House has already said it would veto the bill if it passes.