The allegation - which suggests the Trump administration was eager to lift sanctions imposed by President Barack Obama and that Flynn may have blurred his public and private roles during his brief run at the White House - was outlined in a letter Cummings sent to Rep.
The whistleblower's allegations were made public in a letter Rep. Elijah Cummings (D-MD), the committee's top Democrat, sent to Gowdy Wednesday, to which Gowdy responded with a letter Wednesday evening.
"Mike has been putting everything in place for us", Copson told the whistleblower. "She was sitting at an event, and they met [Alex] Cobson, who, of course, was a business associate of Gen. Flynn at one time, and he began to just talk to her about these things, and that's how she came to us".
Earlier this year, various plans to lift the Russian Federation sanctions circulated through the Trump administration, but Mr. Trump ultimately decided not to repeal the measures.
Flynn pleaded guilty Friday to lying to the Federal Bureau of Investigation during its probe of Russian interference in the presidential election, including about conversations with Russia's ambassador to the USA about sanctions. He called for a bipartisan investigation.
"During their conversation, Mr. Copson informed the whistleblower that he "just got this text message" from General Flynn saying that the project - "involving a joint partnership between the United States and Russian Federation relating to the energy sector in the Middle East" - was "good to go".
"If you have evidence of a crime, you should provide it to the special counsel immediately", Mr Gowdy wrote. He said Flynn did not cash the check, however.
Cummings said that he practiced law for a long time and has interviewed hundreds of witnesses, and he does believe the whistleblower is "very credible".
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. Mr Copson was described by the whistle-blower as responding, "I couldn't be better", and that he was "going to celebrate today". Copson is the managing director of ACU Strategic Partners, a Washington-based company that Flynn said he advised from April 2015 through June 2016, according to a financial disclosure he filed this August.
"When you took over as Chairman this summer, you refused to press the White House to comply with our bipartisan request for documents, and you disregarded new evidence we uncovered about General Flynn's secret effort to work with Russian Federation on a plan to build nuclear reactors in Saudi Arabia", he wrote.
Mr Copson explained that Flynn was making sure that sanctions were going to be "ripped up" as one of the first orders of business and this would allow money to start flowing to the project.
ACU Strategic Partners issued a statement on Wednesday saying, "No member of ACU received any communication in any form from General Flynn during the presidential campaign, the presidential transition, the inauguration, the period following the inauguration when General Flynn served as national security adviser or subsequent to General Flynn's resignation".