Two more senior Democrats have called for an investigation into a share-buying spree by two fossil fuel billionaires with close ties to the Trump administration, after a Guardian investigation raised questions about potential wrongdoing.

Robert Pender and Michael Sabel, the founders and co-chairs of Venture Global, a liquefied natural gas (LNG) company headquartered in Virginia, bought more than a million shares worth almost $12m each in March. The trades took place just days after a meeting with senior White House officials, who then issued a key regulatory permit that helped expand the company’s business in Europe.

Ron Wyden, the ranking member of the Senate finance committee and a member of the energy and natural resources committee, said the transactions should be investigated, drawing parallels with previous Trump administration controversies.

“Corrupt pay-to-play schemes are at the heart of everything the Trump administration does,” Wyden said. “There is no doubt in my mind that these new LNG transactions should be investigated so the American people know the full extent of Trump’s corruption and abuse of office.”

Wyden said investigators uncovered in 2020 that Trump’s energy secretary had inappropriately pressured a Ukrainian state-owned natural gas company to benefit campaign donors, and added that neither Trump nor his energy team faced accountability for those abuses.

Senator Chris Van Hollen echoed those concerns about potential conflicts of interest.

“The Trump administration’s blatant use of cronyism and pay-to-play politics knows no limit. It’s clear that they’re padding the pockets of billionaires at the expense of working Americans,” said Van Hollen, senator for Maryland, member of the Senate banking committee and ranking member of the appropriations subcommittee that oversees the Securities and Exchange Commission and justice department.

“These investments absolutely merit further investigation.”

Van Hollen and Wyden’s intervention comes days after Jeff Merkley, senior Democratic member of the Senate appropriations and budget committees, told the Guardian that the stock trades should be investigated for potential wrongdoing.

“Dirty oil-and-gas bucks are fueling the Trump administration, which should outrage all of us. This latest reporting portrays a pattern of pay-to-play donations and favorable actions by the administration,” Merkley said. “The timing of the stock trades certainly merits investigation for potential conflicts of interest and insider trading.”

All parties involved have denied wrongdoing.

Sabel was among about 20 people who attended an event in April 2024 at Trump’s private club, Mar-a-Lago, when the US president reportedly requested $1bn in campaign donations from the fossil fuel industry in return for favorable legislation. Venture Global was among the “top donors” to Trump’s inauguration, donating $1m, according to the Wall Street Journal.

Individuals connected to Venture Global spent $860,000 on lobbying on Capitol Hill in 2024, and another $810,000 so far this year, according to OpenSecrets, a non-profit campaign finance watchdog. This is more than 12-fold the previous high of $70,000 in 2019.

“This is why we need to get money out of politics,” said Ro Khanna, Democratic representative for California and member of the House oversight and accountability committee, who is leading efforts with the representative Summer Lee to ban Super Pacs.

“LNG exports will raise energy prices for American families and businesses. If Trump is really concerned with the affordability crisis, he should prohibit them and prioritize people over greedy fossil fuel executives,” Khanna added.

The billionaire Republican donors took Venture Global public three days after Trump’s inauguration in January. The weeklong share buying took place days after a meeting with members of Trump’s cabinet including energy secretary Chris Wright, who days later granted the company an export license essential for its expansion plans in Europe.

In response to the Guardian’s findings, a spokesperson for Venture Global last week said the share acquisitions “fully complied with SEC rules and regulations” and the company “strictly adhered to all laws, rules and regulations relating to our interactions with government officials”.

The company has not responded to multiple requests for comment on the growing calls on Capitol Hill for an investigation into the Guardian’s findings.

Karoline Leavitt, the White House press secretary, told the Guardian: “The president has never engaged, and will never engage, in conflicts of interest.”

On his first day back in the White House, Trump issued an executive order rolling back regulations to favor fossil fuel production, including LNG export licences, while revoking existing climate and clean-energy policies. He also withdrew the US from the global climate action treaty, the Paris agreement, and boycotted this year’s UN climate negotiations.

Still, 2025 is on track to be the third-hottest year in history, with catastrophic floods, fires and extreme temperatures killing Americans and causing billions of dollars in damages across the US. Energy bills are rising across the US, with electricity bills up more than 15% in 10 states plus the District of Columbia.

The price hike is mostly due to the rising cost of fossil gas, utilities passing on the cost of upgrade investments to consumers and the rapid unchecked growth of AI and crypto datacenters, which is increasing demand for electricity.

In response to the Guardian’s questions, Leavitt said: “The president has never engaged, and will never engage, in conflicts of interest.”