Manchin, who represents oil and gas-rich West Virginia, holds shares in Enersystems, a contractor for a local power plant that burns waste coal, according to Vice, which first reported on the disclosure. The $492,000 represents more than twice Manchin’s $174,000 senator salary.

Manchin and Arizona Senator Kyrsten Sinema have held up the passing of Biden’s multi-trillion dollar bill, known as the Build Back Better Act, primarily objecting to its price tag.

Its proposals to rapidly replace America’s coal and gas-fired power plants with wind, solar and nuclear energy are now expected to be scaled back following Manchin’s opposition.

In burning coal to generate electricity, Grant Town Power Plant releases more sulfur dioxide and nitrous oxide per unit of energy than any other of the state’s coal plants, according to 2018 calculations by environmental organization Sierra Club.

“In terms of both of those pollutants,” Jim Kotcon, Sierra Club West Virginia chapter’s chairman, told Vice, “it’s still the dirtiest plant operating in West Virginia today.”

Manchin reportedly handed control of Enersystems to his son in 2000, and has moved his holdings in the company into a blind trust to comply with federal rules, the outlet reported.

Yet that does not prevent him from personally profiting, making about $5.2 million from the company since being elected to Congress in 2010, according to Sludge.

Representatives of Manchin have been contacted for comment.

Using the budget reconciliation process, the Biden administration would not require Republican support to pass the bill, but will need every Democrat in the Senate. The bill has already passed the Democrat-majority House.

Manchin has also reportedly objected to the scale of child tax credit expansion plans, and is insisting on a work requirement and cap for households earning more than $60,000 a year, Axios reported on Sunday, citing sources close to discussions.

Revelations about Manchin’s earnings from the coal industry, follows similar criticisms leveled at Sinema.

On Sunday, Representative Alexandria Ocasio-Cortez accused Sinema of putting the interests of “lobbyists over people.”

Ocasio-Cortez is part of a progressive caucus—the Congressional Progressive Caucus, a group of about 95 Democratic members—who have threatened to hold up a $1.2 infrastructure bill, which Manchin supports, until progress has been made with the social spending bill.