In Sen. Joe Manchin III’s hilly West Virginia home county, his family’s business has made millions by taking waste coal from long-abandoned mines and selling it to a power plant that emits air pollution at a higher rate than any other plant in the state.

That enterprise could have taken a hit under a key part of President Biden’s climate agenda, a $150 billion plan to push coal plants toward cleaner energy. One lawmaker, though, played a central role in killing that proposal: Manchin, who has earned hundreds of thousands of dollars annually from the family coal company while using his role as a Democratic swing vote in a 50-50 Senate to dictate Biden’s policies.

When pressed about whether he has a conflict of interest, Manchin bristles. “I have been in a blind trust for 20 years. I have no idea what they’re doing,” the senator told reporters in September, referring to his family’s coal firm. “You got a problem?”

But contrary to his public statements, documents filed by the senator show the blind trust is much too small to account for all his reported earnings from the coal company, as of his latest financial disclosure report, which covers 2020 and was filed in May.

Manchin’s latest financial disclosure report says that the West Virginia family coal business that he helped found and run, Enersystems, paid him $492,000 in interest, dividends and other income in 2020, and that his share of the firm is worth between $1 million and $5 million. He signed a sworn statement saying he is aware of these earnings, underscoring that he is not blind to them.

By contrast, Manchin set up a blind trust with $350,000 in cash in 2012. In his latest financial disclosure report, the senator reported that the Joseph Manchin III Qualified Blind Trust earned no more than $15,000 last year and is worth between $500,000 and $1 million. By design, it is not possible to know precisely what’s in the blind trust. But the financial disclosure records show that it doesn’t include all of Manchin’s income from Enersystems.

If Manchin’s coal interests are not in a blind trust, ethics experts said, it calls into question the impartiality of a senator who in October forced Biden to drop the plan in his Build Back Better bill to phase out the same kinds of coal plants that are key to his family company’s profitability.

The senator’s effort to dismiss questions about his coal interests by declaring he has a blind trust is “misleading and at worst it’s just not true,” said Don Fox, a former general counsel and acting director of the Office of Government Ethics in the Obama administration, who examined Manchin’s financial records at The Washington Post’s request. He cited the vast difference between Manchin’s reported income from the trust and his family’s coal business.

“The question I would ask him would be, when he says it’s in a blind trust, ‘Well, your public financial disclosure report that you sign and swear is true does not have Enersystems in the blind trust,’ ” Fox said. “And if the blind trust is truly blind, how do you know what’s in it?”

Manchin declined an interview request. The Post sent his spokeswoman, Sam Runyon, a list of detailed questions and a copy of the document establishing the blind trust. She did not directly respond to queries about the blind trust and conflict of interest.

Instead, she emailed a statement that said in full: “Senator Manchin is in full compliance with Senate ethics and financial disclosure rules. He continues to work to find a path forward on important climate legislation that maintains American leadership in energy innovation and critical energy reliability, as exemplified by the many provisions to address climate change in the Energy Act of 2020 and the bipartisan Infrastructure Investment and Jobs Act.”

It is legal for Manchin to make millions of dollars from his coal interests even as he chairs the Senate Energy and Natural Resources Committee and legislates on matters affecting the industry. That is because members of Congress are not required to divest their assets to avoid a potential industry conflict.

Senate rules prohibit members from using their position to pass legislation in which “the principal purpose” is to benefit themselves or family members. There is no evidence Manchin has taken action solely to benefit himself or the family company, though critics say that by killing the clean electricity provision in Biden’s agenda, he is helping all coal-related companies — potentially including Enersystems.

Congressional rules are more lenient than, for example, those governing many top executive branch officials, whose assets would be reviewed by the Office of Government Ethics for potential conflicts of interest, making them subject to a requirement to divest, recuse or seek a waiver.

Craig Holman, an ethics expert at Public Citizen, said that regardless of the congressional rules, Manchin’s declaration in the trust that he wants to “avoid any conflict of interest, or any appearance of such a conflict” is undercut by his simultaneous earnings from a coal business and his work against climate policies.

“It is a very blatant conflict of interest,” Holman said, citing the senator’s financial disclosures. “Manchin is not only very wealthy, but most of his assets and wealth are invested in a single industry, coal.”

Holman said Manchin’s financial position is one of the most conflicted of any member of Congress he has studied because so much of the senator’s financial stake is in the coal industry while he is playing a key role on climate policies. Nonetheless, he said, “what Manchin is doing is not illegal. The conflict of interest code for Congress is just way too weak.”

Sen. Tina Smith (D-Minn.), who sought for months to convince Manchin to support the plan to transition power companies to cleaner forms of energy, said the West Virginia senator ultimately balked. Manchin’s opposition effectively killed one of the most far-reaching climate policies in the bill, outraging environmentalists and leading to an increased focus on his family’s coal business and his own earnings.

“After working on the Clean Electricity Performance Program, which I think is the strongest and best way of getting the utility sector to net-zero emissions as quickly as possible, Sen. Manchin ultimately said he just couldn’t get there,” Smith said in an interview. “And I think that was a mistake — I think the [program] would have been a powerful tool to get the emissions reductions we need, while keeping utility rates low.”

She stressed that she is still having “good conversations” with Manchin and is negotiating on other parts of the bill affecting climate change, but she has “no expectation that any kind of clean electricity plan will be included.”

Manchin could further scale back Biden’s climate change efforts. The senator has also objected to a measure in the Build Back Better bill designed to reduce emissions of methane, the main component of natural gas, and a tax credit for electric cars. He has not yet announced his support for the Democrats’ spending bill.

Questions about a conflict between Manchin’s coal interests and his government service go back decades, a review by The Post found.

Manchin helped found and became president of Enersystems, a coal brokerage firm, in 1988. One of its customers since 1993 has been a power plant in Grant Town, W.Va., that uses waste coal to produce energy.

In the mid-1990s, when Manchin was a state senator, he backed legislation that gave plants such as the one in Grant Town a property tax break. When a group of local citizens complained that Manchin had a conflict of interest, he responded that he had avoided any ethical problem by giving the break to all similar projects.

Had the bill only benefited the Grant Town plant, Manchin said at the time, “I would have excused myself from voting,” according to a contemporaneous account in the Charleston Gazette. But by backing a broad measure, Manchin said ethics officials told him it was allowed, notwithstanding the benefit for Grant Town.

After Manchin was elected West Virginia’s secretary of state in 2000, he gave control of Enersystems to his son Joseph Manchin IV, who still runs it. The younger Manchin did not respond to a request for comment.

After Manchin was elected governor in 2005, he said he put his company shares in a blind trust. He reported receiving hundreds of thousands of dollars from his coal business on a state financial disclosure form in 2009 and 2010, and told the news service Greenwire in 2011 that his holdings had “absolutely not” affected his policies, adding, “I have been in a blind trust for a long time.”

In his successful 2010 bid for the U.S. Senate, Manchin ran an ad that showed him shooting at President Barack Obama’s proposed legislation to address climate change “because it’s bad for West Virginia.” Between 2011 and 2020, Manchin earned $4.8 million from Enersystems, according to a tally by the Center for Responsive Politics. His net worth as of 2020 was between $4.4 million and $12.8 million, the center said.

Enersystems is a private company based in Fairmont, W.Va., near Manchin’s hometown of Farmington. Public records show that the business is among those that benefit from federal programs to clean up long-shuttered coal mines, where mountains of mining debris, known as waste coal, have been piled and abandoned. The company sells the waste coal to the only power plant in the state that still burns it: the Grant Town Power Plant, an 80-megawatt electricity-generating facility in Manchin’s home county of Marion.

Compared with ordinary coal plants, power plants that burn waste coal, or what the industry calls “gob,” are dirtier and don’t generate as much electricity. The Grant Town plant emits more greenhouse gases and the main components of acid rain — nitrogen oxides and sulfur dioxide — into the air per megawatt-hour of electricity produced than any other power plant in West Virginia, according to the Environmental Protection Agency’s most recent data. Only a handful of waste-coal-burning plants still operate nationally. They are such heavy polluters that the Trump administration created a separate category for them, weakening the air pollution standards they had to meet.

“Burning waste coal, like burning trash, turns pollution on the ground into pollution in the air,” said Eric Schaeffer, executive director of the Environmental Integrity Project, a nonprofit founded by former EPA officials. The environmental benefits of clearing waste coal from mining sites are questionable, he added. Although removing the piles of gob can reduce acid runoff, the process of burning it creates an enormous amount of ash that can release toxins into streams or groundwater.

The Manchin family doesn’t own or operate the Grant Town plant, which is run by American Bituminous Power Partners, a limited partnership registered in Delaware. But records of coal transactions from last year suggest the power plant is Enersystems’ primary customer. It is the only publicly recorded buyer of Enersystems’ waste coal.

In response to written questions from The Post, American Bituminous Power Partners Executive Director Ken Niemann said the Grant Town plant “is in full compliance with all its state and federal air emissions controls and limitations.”

As the economics of burning coal have become less favorable, the Grant Town plant has come close to shutting down at least twice. In 2006, when Manchin was governor, the state’s Public Service Commission rescued the plant by approving rate increases, which the utility passed on to customers. The commission’s chair at the time was a Manchin appointee.

Those higher prices were supposed to be temporary until 2017. But by 2015, the power plant’s owners were back before the commission, claiming financial difficulties. The commissioners sided with the plant, and the higher rates became permanent.

The Grant Town plant faced a new threat this year: Democrats’ plans to rapidly shift the electricity sector away from coal and toward cleaner sources of energy. The clean electricity program would have rewarded utilities for purchasing more electricity from wind, solar and other emissions-free sources — and penalized those that did not.

If the program had become law, the power company that buys electricity from the Grant Town plant would have faced growing financial pressure to shift away from coal power, increasing the odds that Grant Town would eventually close, said James Van Nostrand, director of West Virginia University law school’s Center for Energy and Sustainable Development.

The clean electricity program “would have helped us out a lot,” Van Nostrand said. West Virginia’s embrace of coal power over less expensive alternatives like gas, wind and solar has contributed to a decade of rising electricity bills. According to Van Nostrand’s analysis, between 2010 and 2019 West Virginians’ electricity costs increased about five times more than the national average.

“By definition, if the federal government is going to help us transition to cheaper, cleaner electricity, then our electricity bills would either go down or wouldn’t go up as fast as they are now,” he said.

In 2019, Manchin co-authored an op-ed with Sen. Lisa Murkowski (R-Alaska) in The Post that said: “There is no question that climate change is real or that human activities are driving much of it. We are seeing the impacts in our home states.” They said they were working to find “pragmatic policies that can draw strong and enduring support” and pinned much of their hope on what they called “the next scientific breakthrough” for “game-changing technology.” They opposed what they called “drastic, unattainable measures to reduce greenhouse-gas emissions.”

Manchin’s role as the potentially decisive vote in the Senate and his opposition to efforts at abandoning the filibuster have given him outsize power, which he’s used in part to reduce the Build Back Better bill from more than $3 trillion to $1.75 trillion.

Manchin has argued that the clean electricity plan he insisted on removing from the bill is unnecessary because coal companies are already moving toward other energy sources. “The only thing they want us to do is pay $150 billion for what’s already happening,” Manchin told reporters in October in explaining his opposition to the measure. “We’ve transitioned.”

The legislation that passed the House last month still contains $555 billion in tax credits, grants and other efforts to lower planet-warming greenhouse gases, which would be the largest clean energy investment in U.S. history. The bill’s tax incentives would make it easier to install solar panels, build wind turbines and retrofit buildings with energy-saving upgrades. Electric vehicles would become less expensive, reducing a barrier that has prevented many Americans from purchasing them.

Around the time Manchin helped kill the clean electricity provision, he was asked during a walk with reporters on Capitol Hill about whether he has a conflict of interest and was pressed on the fact that his son runs the family coal company. Manchin responded, “I’m very proud of my son. He does a good job. You’d do best to change the subject now.”

Manchin’s critics said that while the senator was not violating any law, he is violating the premise of his promise to avoid the appearance of conflict of interest.

Dylan Hedtler-Gaudette, manager of government affairs at the Project on Government Oversight, said the best way to prevent such a conflict of interest would be to require members of Congress to divest most investments. If such a policy were adopted, Manchin would be required to liquidate his shares in the coal company and put the assets in a blind trust, and authorize a trustee to invest the money in any way deemed appropriate, and without his knowledge.

“Under the current framework, you are not required to divest anything,” he said. “I think there should be someone in Congress who introduces a bill that says, ‘Look, if you become a member of Congress, you have to divest basically everything except for a widely diversified mutual fund.’ ”

But Hedtler-Gaudette said he has not found a single member of Congress willing to sponsor such legislation. As a result, he hopes Manchin’s case will prompt legislators to consider requiring divestment of any asset — not just publicly traded stock — that could be perceived as a conflict of interest.

“If you don’t like it, that’s fine,” Hedtler-Gaudette said. “There isn’t anyone who requires you to be a member of Congress.”

Alice Crites contributed to this report.

Correction: An earlier version of this article said that Sen. Joe Manchin III told reporters in September, “The only thing they want us to do is pay $150 billion for what’s already happening.” The quote is from October. This article has been corrected.