WASHINGTON (Reuters) - U.S. Senator John Kerry ratchets up the fight to pass his well-telegraphed bill to combat global warming on Wednesday, unveiling legislation just as the Gulf of Mexico oil disaster complicates the measure's already slim chances of passage.
Kerry, a Democrat, and Senator Joseph Lieberman, an independent, are to unveil the bill at 1:30 p.m. EDT (1730 GMT).
Most of the details of the bill, which aims to cut planet-warming emissions in the United States by 17 percent in the next decade, already have been leaked.
Crucially, Republican Senator Lindsey Graham, who helped write the bill but withdrew from talks over the immigration reform debate, will not attend the ceremony.
The bill still has provisions to encourage offshore drilling but would allow U.S. states to prohibit offshore oil activity within 75 miles of their coasts.
But analysts said that may not be enough to win drilling opponents from coastal states as concerns mounts over the growing the gushing oil well in the Gulf of Mexico.
Backers of the bill had hoped to bring in wavering Democratic lawmakers, and Graham had been expected to help bring in other Republicans to reach the 60 votes needed to pass the bill.
The White House on Wednesday promised to work to pass the bill into law. President Barack Obama's top energy and climate advisor, Carol Browner, told reporters in a conference call that the administration would review details of the bill.
But it is unclear if Obama is willing put the same kind of political capital behind the climate bill as he did for healthcare legislation earlier this year, as some advocates have been seeking.
Without a big White House push, the bill faces slim chances this year with the already clogged Congressional schedule, such as dealing with financial industry reform and a Supreme court nomination.
Mid-term elections later this year also will distract many lawmakers from focusing on legislation that could boost prices for gasoline and electricity in coming years as the country struggles out of recession.
"Everyone knows this is Congress's last, best chance to pass comprehensive climate and energy legislation," Kerry said late Tuesday. If it fails, he added, "Congress will be rendered incapable of solving this issue."
The bill includes provisions for boosting nuclear power and offshore drilling in order to help win votes from states where the economies depend on energy production. Earlier versions of the legislation relied more on boosting alternative energy such as wind and solar.
Analysts said measures for drilling may hurt the chances of the bill.
"The Gulf of Mexico spill has turned offshore drilling -- an issue that once greased the wheels of the grand bargain -- into a political toxin," said Kevin Book, analyst at ClearView Energy Partners, who until a month ago had been optimistic about the bill's chances.
Still, environmentalists said the bill must be passed this year to give businesses confidence to move forward with clean energy sources.
Many utilities with big investments in low-carbon nuclear power, natural gas or wind and solar power hope to benefit from a crackdown on greenhouse gases.
Utilities such as FPL Group, Duke Energy and Exelon have lobbied alongside environmental groups for the climate bill as has General Electric, a manufacturer of clean coal and natural gas systems for power plants and wind turbines.
"Enacting a strong federal clean energy and climate program will give business the certainty it needs to unleash significant investments that will create jobs and grow our economy," said Eileen Claussen, the president of the Pew Centre on Global Climate Change.
(Additional reporting by Richard Cowan; Editing by Russell Blinch and Bill Trott)