The investigation marks the Democrats’ latest salvo against the oil industry just as executives have increased their contributions to the former president’s run against Joe Biden.

Congressional Democrats launched another salvo against the oil industry Thursday, this time investigating what executives may have promised or been promised at a dinner with former President Donald Trump where he asked them for $1 billion in campaign donations.

The letters sent by Senate Budget Chair Sheldon Whitehouse (D-R.I.) and Senate Finance Chair Ron Wyden (D-Ore.) to nine oil companies and industry trade associations is the latest in a slew of investigations Democrats have opened into the oil industry in recent weeks. Democrats have upped the political ante against the industry just as oil company executives have started opening their wallets to back Trump’s campaign against President Joe Biden.

The committees sent the letters to Chevron, Exxon Mobil, Continental Resources, Chesapeake Energy, Occidental Petroleum, Venture Global LNG, Cheniere Energy, EQT Corp. and trade association American Petroleum Institute. The inquiries focus on whether the companies discussed potential industry-friendly policies Trump might adopt in a second administration in return for their financial support.

The senators also ask for information on what policy-related documents industry lawyers might be ready to supply Trump for his signature if he once again sits in the Oval Office, an issue first reported by POLITICO.

“Such an obvious policies-for-money transaction reeks of cronyism and corruption,” the senators write in their letters obtained by POLITICO. ”This solicitation, coupled with troubling reports that fossil fuel interests and other companies have been drafting language for use in executive orders favorable to their businesses during a possible second Trump Administration, demand immediate additional inquiry.”

Spokespeople for the companies did not immediately reply to questions. An API spokesperson said the meeting was nothing out of the ordinary.

“This is yet another election-year stunt to distract from America’s need for more energy, including more oil and natural gas, to power our economy and combat persistent inflation,” API spokesperson Andrea Woods said. “API meets with candidates and policymakers to discuss the need for sound energy policies, and this meeting was no different.”

Thursday’s letters follow an earlier round of missives Wednesday sent by House Energy … Commerce ranking member Frank Pallone (D-N.J.) seeking information from Exxon, Chevron and other industry entities on their possible communications with officials from the oil producing cartel OPEC+. Pallone opened the investigation after the Federal Trade Commission alleged that the former chief executive of Pioneer Natural Resources, a company now owned by Exxon, attempted to collude with rival companies and OPEC to fix oil production at levels that would keep prices elevated.

Democrats on the House Natural Resources Committee on Thursday urged Chair Bruce Westerman (R-Ark.) to also open an investigation into the collusion allegations.

“Over the last two years, you and your colleagues have repeatedly expressed concern about high gas prices, trying to blame environmental protections and efforts to hold polluters accountable, even while the U.S. has been the number one producer of oil and the number one producer and exporter of gas in the world, and industry profits have soared,” committee ranking member Raul Grijalva (D-Ariz.) wrote in a letter to Westerman. “The complaint released by the FTC provides evidence for a different explanation that is more consistent with that given by Committee Democrats: Big Oil companies conspired to drive up their own profit at the expense of consumers by colluding with cartels consisting of countries that pose national security threats to the U.S.”

A spokesperson for committee Republicans did not immediately respond to questions.

Also on Wednesday, Whitehouse and Rep. Jamie Raskin (D-Md.) asked the Department of Justice to review information Congressional Democrats have accumulated showing what they called the industry’s misleading the public about the effects of their products on climate change and their plans to combat it.

That Democrats are increasing their scrutiny of the oil industry just as executives are contributing millions of dollars to Trump’s reelection efforts may not be coincidental, said Tyson Slocum, energy program director at Public Citizen, a progressive good governance advocacy group.

“It’s right on policy, it’s right on politics,” Slocum said of the recent spate of investigations.

“You got the FTC showing attempts at collusion with OPEC,” Slocum continued. “That’s a scandal. You got Trump saying in front of tons of people ‘If you give me a billion dollars, I’m going to give you everything you want,’ the Democrats need to investigate this. If Democrats can land a few punches with an accurate narrative that Big Oil colluded with Saudi Arabia and is buying favors from Donald Trump, I think that’s good politics.”