Sen. Joe Manchin III (D-W.Va.) speaks to reporters after a debate with challenger Patrick Morrisey (R) in Morgantown, W.Va., on Nov. 1, 2018. (Ray Thompson/AP)

Billionaire Democratic activist Tom Steyer said Thursday that Sen. Joe Manchin III should not be elevated to ranking minority member of the Senate Energy and Natural Resources Committee, becoming the latest potential 2020 White House contender to oppose the West Virginia Democrat, who has embraced some of President Trump’s environmental initiatives.

Steyer’s statement comes one day after Washington Gov. Jay Inslee (D) said Manchin “simply can’t be trusted to make the bold, progressive decisions we need” on the committee. Inslee is also considering a 2020 presidential bid.

“Democrats must offer a bold, positive path forward — but Senator Manchin does not offer that vision and should not be the Democratic leader on the Senate Energy and Natural Resources Committee,” Steyer said. “Senate Democrats owe it to their constituents to tell the truth, acknowledge the urgent climate crisis we’re in and do what’s right — instead of what’s politically expedient for them.”

Steyer, a former hedge fund manager who is best known for his campaign to impeach Trump, has long been a prominent supporter of efforts to combat climate change.

Manchin’s office declined to comment. The senator told HuffPost’s Igor Bobic at the Capitol on Thursday afternoon that his message to his progressive critics is: “Come in and talk to me. The door’s open.”

Intraparty battles over congressional committee assignments are usually closed-door affairs that attract little attention beyond Washington. But the recent statements about Manchin by Steyer and Inslee are a rare instance of one such skirmish becoming a key issue for potential members of the 2020 White House field.

In what some have seen as an olive branch to environmental groups, Manchin voted against confirming Trump appointee Bernard McNamee on Thursday to serve on the Federal Energy Regulatory Commission. Manchin had originally backed McNamee, but in a statement Wednesday, he said the Energy Department official, who was part of a team that drafted a plan to rescue the coal industry, did not have a strong enough record on climate change.

Sen. Maria Cantwell (D-Wash.), the current ranking minority-party member on the Energy and Natural Resources Committee, is expected to become the top Democrat on the Commerce Committee in the next Congress, with Manchin poised to take her spot on the energy panel. The development has prompted alarm among liberal and environmental groups, which worry that the West Virginia Democrat will stymie their climate agenda.

Some activists are calling for Sen. Bernie Sanders (I-Vt.) to block Manchin by claiming the top Democratic spot on the energy committee. But Sanders, a potential 2020 contender himself, is expected to remain in his spot as the top Democrat on the Budget Committee instead.