Early versions of the bill had $555 billion in tax breaks for clean energy such as wind and solar power as well as batteries and nuclear reactors.

Still, Wednesday's package would cut U.S. emissions 40% by 2030, a summary released by Senate Majority Leader Chuck Schumer's office said.

The baseline for the cut was 2005, Leah Stokes, a professor of climate and energy policy at the University of California, Santa Barbara, who advised Democrats on the bill.

Clean energy backers said it would go a long way toward President Joe Biden's goal of decarbonizing the U.S. economy by 2050.

"It's an absolutely transformative package," said Stokes. She said the bill would boost American manufacturing in everything from batteries to solar energy to electric vehicles and contains the largest environmental justice investment ever.

Biden, who has faced soaring oil prices and record gasoline prices that have helped drive inflation to 40-year highs, said in statement the bill would "improve our energy security and tackle the climate crisis."

Heather Zichal, the head of American Clean Power, a group of renewable energy companies, said Congress is now close to passing "the biggest climate and clean energy investment in American history."

Democrats hope to pass the bill by a simple majority in the Senate. The bill must also pass the House, where Democrats also have a razor-thin majority, and be signed by Biden.

It contains a "methane emissions reduction program" to cut leaks of the potent greenhouse gas methane from drilling of natural gas, according to the summary.

It was not immediately clear if a methane fee many Democrats had wanted on the emissions that would penalize energy companies for the leaks had been modified.

Senator Joe Manchin, a conservative Democrat and the swing vote who has received more donations from oil and gas companies than any other lawmaker in recent years, had pushed for companies to not face the fee if they were unable to build a pipeline to carry the gas to market.

Manchin said the bill will invest in hydrogen, nuclear power, renewables, fossil fuels and energy storage.

"This bill does not arbitrarily shut off our abundant fossil fuels," said Manchin, who has sought for months to preserve federal oil and gas leasing projects and natural gas pipelines in talks on the bill.

Democrats, he added, "have committed to advancing a suite of commonsense permitting reforms this fall that will ensure all energy infrastructure, from transmission to pipelines and export facilities, can be efficiently and responsibly built to deliver energy safely around the country and to our allies."

The measure has more than $60 billion in environmental justice programs to fight pollution and address public health harms in disadvantaged communities. It also has $20 billion for "climate-smart" agriculture practices, the summary said without providing details.

The bill contains a $10 billion investment tax credit to build clean technology manufacturing plants for EVS, wind turbines and solar panels, the summary said.

It also has an estimated $30 billion investment in production tax credits to accelerate U.S. manufacturing of batteries and wind and solar power components and critical minerals processing.