WASHINGTON — Michael T. Flynn, President Trump’s former national security adviser, told a former business associate that economic sanctions against Russia would be “ripped up” as one of the Trump administration’s first acts, according to an account by a whistle-blower made public on Wednesday.
Mr. Flynn believed that ending the sanctions could allow a business project he had once participated in to move forward, according to the whistle-blower. The account is the strongest evidence to date that the Trump administration wanted to end the sanctions immediately, and suggests that Mr. Flynn had a possible economic incentive for the United States to forge a closer relationship with Russia.
Mr. Flynn had worked on a business venture to partner with Russia to build nuclear power plants in the Middle East until June 2016, but remained close with the people involved afterward. On Inauguration Day, according to the whistle-blower, Mr. Flynn texted the former business associate to say that the project was “good to go.”
The account is detailed in a letter written by Representative Elijah Cummings of Maryland, the top Democrat on the House Oversight Committee. In the letter, Mr. Cummings said that the whistle-blower contacted his office in June and has authorized him to go public with the details. He did not name the whistle-blower.
“These grave allegations compel a full, credible and bipartisan congressional investigation,” Mr. Cummings wrote.
Mr. Flynn has been under investigation by Robert S. Mueller III, the special counsel investigating Russia’s attempts to disrupt last year’s election, for calls he made last December to Sergey I. Kislyak, the Russian ambassador to the United States at the time. Mr. Flynn pleaded guilty on Friday to lying to the F.B.I. about the nature of his calls, during which the men discussed the sanctions that the Obama administration had just imposed on Russia.
In his letter, Mr. Cummings also said that his staff had been in consultations with Mr. Mueller’s team, which brought the criminal charge against Mr. Flynn. Staffers for the special counsel asked Mr. Cummings not to make the whistle-blower’s account public until “they completed certain investigative steps,” he wrote.
According to the account detailed in the letter, the whistle-blower had a conversation on Inauguration Day with Alex Copson of ACU Strategic Partners, a company that hired Mr. Flynn in 2015 as an adviser to develop a plan to work with Russia to build nuclear power plants throughout the Middle East. Mr. Flynn served as an adviser until June 2016.
During the conversation, Mr. Copson told the whistle-blower that “this is the best day of my life” because it was “the start of something I’ve been working on for years, and we are good to go.” Mr. Copson told the whistle-blower that Mr. Flynn had sent him a text message during Mr. Trump’s inaugural address, directing him to tell others involved in the nuclear project to continue developing their plans.
“This is going to make a lot of very wealthy people,” Mr. Copson said.
Attempts to reach Mr. Copson on Wednesday were unsuccessful. A lawyer for Mr. Flynn declined to comment.
The letter went on to say that “Mr. Copson explained that General Flynn was making sure that sanctions would be ‘ripped up’ as one of his first orders of business and that this would allow money to start flowing into the project.”
President Obama first imposed economic sanctions on Russia in 2014, after Russia’s military incursions in Crimea and Ukraine, and again last December to punish Russia for its attempts to disrupt the United States presidential election.
Earlier this year, various plans to lift the Russia sanctions circulated through the Trump administration, but Mr. Trump ultimately decided not to repeal the measures. Mr. Flynn lasted just 24 days as national security adviser before he was forced out amid questions about whether he lied to administration officials about the nature of his phone calls with Mr. Kislyak.
Mr. Cummings sent the letter to the chairman of the House Oversight and Government Committee, Trey Gowdy, Republican of South Carolina, and asked him to investigate the whistle-blower’s claims. The whistle-blower, Mr. Cummings said, is willing to meet with Mr. Gowdy if he agrees to protect the person’s identity.
“I do not bring this whistle-blower to your attention lightly,” Mr. Cummings said. “I have attempted to advance this investigation without exposing individuals to personal or professional risk. But the exceptionally troubling allegations in this case — combined with ongoing obstruction from the White House and others — have made this step necessary.”
Mr. Cummings said Mr. Gowdy should subpoena the White House and the Flynn Intelligence Group, Mr. Flynn’s former company, for documents that the House committee had requested in March but had not yet been provided. The subpoena to the White House should be for “all documents — including emails and text messages sent on personal devices” about Mr. Flynn’s foreign contacts, payments and efforts to promote the proposal. Mr. Cummings said that Mr. Gowdy should subpoena Mr. Flynn, Mr. Copson and four others to testify before the panel.
Mr. Gowdy and Mr. Cummings have a long history of clashing publicly over politically charged investigations. Mr. Gowdy was the chairman of the special committee that investigated the 2012 attacks in Benghazi, Libya, and Mr. Cummings was that panel’s ranking member. As part of that investigation, Mr. Gowdy also scrutinized Hillary Clinton’s use of a private email account when she was secretary of state.
In the letter, Mr. Cummings appeared to try to anticipate an argument that Mr. Gowdy might make — that he cannot investigate the whistle-blower’s claims as long as Mr. Flynn was still under investigation by Mr. Mueller’s team.
“As chairman of the Benghazi select committee, you pursued your investigation of Hillary Clinton during an ongoing criminal investigation,” Mr. Cummings wrote.