The battle over the bill’s energy provisions is just one fight playing out in Washington as industries have mobilized armies of lobbyists from sectors ranging from Big Pharma to manufacturing around what could be the biggest expansion of federal programs and spending since Franklin Delano Roosevelt’s New Deal.

U.S. House committees started writing the legislation last week, creating or expanding several social programs. The Ways and Means Committee will tackle the tax portion of the bill starting Tuesday.

Democrats want to push the legislation through both chambers by the end of the month using a procedure that averts Senate filibustering. But razor-thin majorities require the fractious Democratic caucus to overcome divides between progressives and moderates over the size and scope of the bill.

In the evenly divided Senate, it takes just one Democratic defection to sink the entire package, a fact that hasn’t escaped industry and advocacy groups spending millions to try to sway the handful of Democratic votes considered in play, including Manchin’s.

“If all else is equal and I happen to be a lobbyist on the side of ‘kill the bill,’ I automatically have an advantage,” said Timothy LaPira, a political science professor at James Madison University who studies lobbying.

The fossil fuel industry is pushing to block dozens of proposals in the measure that it argues would hurt domestic oil and gas production in the name of fighting climate change. The American Petroleum Institute is running broadcast and digital ads in key states and congressional districts as part of a seven-figure campaign to block a fee on methane emissions, among other energy provisions, from the bill, arguing they would cripple an entire industry and affect thousands of workers.

On the other side, advocacy groups including the League of Conservation Voters and Climate Power have launched their own high-dollar media campaigns supporting the measures as a response to violent storms, floods, fires and droughts caused by global warming.

Manchin, the Democratic senator from coal-dependent West Virginia who is also chairman of the Energy and Natural Resources Committee, has criticized the size of the package and demanded a “strategic pause” on the reconciliation plan, potentially imperiling it in the evenly divided Senate.

Sarah Bryner, director of research for the Center for Responsive Politics, which tracks lobbying, said Manchin is probably the most important lawmaker in determining the fate of the energy provisions and the bill itself.

“His history, his policy positions, and the state he represents all come together to make him a valuable target for all actors in this fight,” Bryner said.

Manchin will clearly use his leverage to get what he wants with the bill, and both supporters and opponents think it’s possible to win him over, she said. “If they thought he was a lost cause, the conversation would be different,” she said.

Biden is “looking forward to speaking with him,” the president said. “Joe, at the end, has always been there. He’s always been with me. I think we can work something out.”

Manchin’s campaign and leadership political action committees received almost $400,000 from the oil and gas industry since 2017, and he was the sector’s top recipient in Congress through the first six months of 2021 with $179,450, according to the Center for Responsive Politics.

Since 2010, the political action committee for the American Gas Association, which represents utilities such as Southern Co. and DTE Energy Co., has donated $17,000 to Manchin, according to Federal Election Commission data. Exxon Mobil’s political action committee has contributed $12,500 and the American Petroleum Institute’s political action committee has donated $10,000 since 2012.

Earlier this month, as Democrats prepared to insert a fee totaling $1,500 a ton on methane, a potent greenhouse gas, the Gas & Oil Association of West Virginia sent Manchin a letter imploring him to reject it.

“This harmful energy tax legislation would raise costs for all Americans, discourage capital investment that incentivizes innovation, and provide virtually no environment benefit,” Charlie Burd, the group’s executive director, wrote.

Manchin’s office declined to comment. But Manchin appeared on three Sunday political shows to defend his position that the bill shouldn’t be rushed, would spend too much and that the clean energy provisions aren’t needed because the U.S. is already transitioning away from fossil fuels.

The West Virginia senator denied accusations from progressive Rep. Alexandria Ocasio-Cortez and other Democrats that he meets weekly with energy lobbyists and is beholden to the fossil-fuel industry, saying on CNN’s “State of the Union” on Sunday “it’s totally false.””You’re entitled to your opinion, you’re just not entitled to create your own facts to support your opinion,” Manchin said on NBC’s “Meet the Press.”

Vermont Sen. Bernie Sanders said on ABC’s “This Week” on Sunday that Manchin digging in his heels threatens to kill both the reconciliation bill and the $550 billion infrastructure measure that progressives want linked with it. But Manchin said on CNN, “who’s digging in the heels here?”

Beyond energy issues, a large coalition led by the U.S. Chamber of Commerce is lobbying against the $3.5 trillion plan. It would raise taxes on corporations and high-income individuals and overhaul prescription-drug pricing to pay for a massive expansion of social and health-care programs.

With so many provisions in the bill affecting different companies and sectors of the U.S. economy, the business lobbies are coordinating activities, said Neil Bradley, the Chamber’s executive vice president and chief policy officer.

Bradley described the proposal as “everything under the sun plus the kitchen sink.”

The National Association of Manufacturers, which joined the Chamber in backing the infrastructure bill, is focusing on the tax provisions as well as the drug pricing and labor measures, said Aric Newhouse, senior vice president of policy and government relations for the group. NAM is launching a six-figure ad campaign in Washington and key states.

Groups backed by the pharmaceutical industry, including PhRMA, the sector’s largest trade group, have spent more than $18 million on advertising since July against allowing Medicare to negotiate drug prices as a way to lower costs.

That campaign targets what it calls “government price-setting,” according to a group called Patients for Affordable Drugs Now, which is airing its own ads against “Big Pharma lies and scare tactics.”

The pharmaceutical industry says it’s willing to work with Congress on reforms, but that the Democrats’ proposal would limit patient access to drugs and stifle new products. Funding for research and development at Merck & Co. would be reduced almost by half, and many small firms wouldn’t survive, Executive Chairman Kenneth Frazier said on a call Wednesday with reporters.

“We need to be frank that the proposals that we’re seeing from Congress would devastate this industry,” he said.

At the same time, Democrats and allied groups are mobilizing to support the package. Independent Senator Bernie Sanders of Vermont is barnstorming Iowa and other Republican areas. A group of 11 leading progressive organizations is calling for “a major lobbying blitz.”

AARP, a non-profit that focuses on issues faced by people over 50, launched a campaign last month with TV and radio ads to push lawmakers to include provisions to lower drug prices. The group is also urging activists and social media followers to tweet photos of their receipts for expensive medications to their lawmakers.

In August, the Democratic National Committee organized a bus tour in more than 10 states to promote Biden’s economic agenda. Building Back Together, an advocacy group that supports the president’s plan, said it’s leading a coalition of progressive organizations in a campaign that began in August, spending $110 million on state actions, events and ads.