As President Trump delivered his inaugural address, national security adviser Michael Flynn texted a former business partner that a private nuclear power project that would require lifting sanctions on Russia was “good to go,” a senior House Democrat said in a letter released Wednesday.

Quoting a confidential informant, Rep. Elijah Cummings, the top Democrat on the House Oversight and Government Reform Committee, wrote that Alex Copson, managing partner of ACU Strategic Partners, told the informant that Flynn would see that the sanctions on Moscow were “ripped up.”

In the letter to Rep. Trey Gowdy, the panel’s GOP chairman, Cummings demanded that Gowdy subpoena documents on the nuclear power plan from the White House, Flynn, Copson, their partners and associates, Reuters reported.

Cummings said he had found the unnamed informant to be “authentic, credible and reliable,” and offered to produce the person for Gowdy.

“These grave allegations compel a full, credible and bipartisan congressional investigation,” Cummings wrote, according to the New York Times.

The account is the strongest evidence yet that Team Trump wanted to end the sanctions immediately, and suggests that Flynn had a possible economic incentive for the US to establish a closer relationship with Russia.

As the whistleblower chatted with Flynn’s associate during an Inauguration Day celebration on Jan. 20, Flynn sent texts saying the associate’s nuclear proposal was “good to go,” the whistleblower said.

Flynn also informed the associate that his business partners could move forward with their project, which aimed to construct a network of nuclear reactors across the Mideast with support from Russian and other international interests, the whistleblower said.

He has been under investigation by Special Counsel Robert Mueller — who is investigating Russia’s attempts to disrupt last year’s election — for calls he made last December to then Russian Ambassador Sergey I. Kislyak.

Flynn has pleaded guilty to lying to the FBI about the nature of his calls, during which the men discussed the sanctions that the Obama administration had just imposed on Russia.