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 Russian Federation to build nuclear power plants throughout the Middle East. Mr. Flynn served as an adviser until June 2016.
In a reply late Wednesday, Gowdy declined, saying he shared Cummings' letter with Rep. Michael Conaway, R-Texas, and Rep. Adam Schiff, D-Calif., the chairman and ranking Democrat heading the House intelligence committee inquiry into Russian involvement in the 2016 election.
The whistleblower came forward this summer and spoke to the committee about attending an inauguration party and meeting Alex Copson, managing partner of ACU Strategic Partners. On Inauguration Day, according to the whistle-blower, Mr. Flynn texted the former business associate to say that the project was "good to go". He said Flynn did not cash the check, however.
"This is going to make a lot of very wealthy people", Mr. Copson said.
The letter said that if this witness account is accurate, Mr Trump's national security adviser "was trying to manipulate the course of worldwide nuclear policy for the financial gain of his former business partners". Cummings described the account in a letter Wednesday to the panel's Republican chairman, Rep. Trey Gowdy of SC.
"I do not bring this whistleblower to your attention lightly", Cummings, the Baltimore lawmaker and top Democrat on the committee wrote in the letter.
On Friday, Flynn pleaded guilty to lying to the Federal Bureau of Investigation in a voluntary interview conducted only four days following his alleged text messages to Copson.
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Mr. Gowdy and Mr. Cummings have a long history of clashing publicly over politically charged investigations.
Cummings said the whistleblower, whom he did not identify in the letter, "fears retaliation", but would speak with Gowdy if he agrees to protect the whistleblower's identity. The witness could not read the text, but he saw that the time stamp was 12:11 p.m., according Cummings's letter.
The witness told congressional investigators that he was "extremely uncomfortable" with the conversation, Cummings wrote, and took brief notes about the discussion during the inaugural event.
"Mr. Copson explained [to the whistleblower] that General Flynn was making sure that sanctions would be 'ripped up", Cummings wrote.
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".
Flynn was involved in the Middle Eastern nuclear project from spring 2015 to the end of 2016, according to recent financial disclosure filings, a period that overlapped with his role as a prominent adviser to Trump's campaign and transition. But it's not. Cummings provided hard evidence that he wants to form the basis of a subpoena created to uproot what really happened.
The whistle-blower's account is detailed in a letter from Rep.