WASHINGTON — Donald Trump was just 11 minutes into his presidency when his choice for national security adviser, Michael Flynn, texted a former business partner to say an ambitious U.S. collaboration with Russia to build nuclear reactors in the Middle East was "good to go," according to a new whistleblower account.

As Trump delivered his inaugural address, says the unnamed whistleblower, Flynn directed Alex Copson, managing director of ACU Strategic Partners, to inform their business partners "to put things in place."

The whistleblower also says that Flynn assured Copson that U.S. sanctions on Russia that could block the nuclear project would be "ripped up" once Trump was inside the White House.

The account from the anonymous whistleblower is detailed in a letter from the top Democrat on the House Oversight and Government Reform Committee to his Republican counterpart asking that the panel subpoena Flynn, Copson, the White House and others involved in the alleged plan.

Click here to read the letter

"Our Committee has credible allegations that President Trump's National Security Advisor sought to manipulate the course of international nuclear policy for the financial gain of his former business partners," Rep. Elijah Cummings, D-Md., wrote in a letter sent Wednesday to Committee Chairman Trey Gowdy, R-S.C.

Michael Flynn appears to look at his phone during President Trump's inauguration ceremony. House Oversight and Government Reform Committee

The whistleblower first approached staff on the Oversight Committee in June just after Newsweek published an account of Flynn's role in pursuing a joint U.S.-Russian plan to build nuclear power plants throughout the Arab world, to be financed by Saudi Arabia, according to the letter.

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Copson did not immediately respond to a request for comment. Flynn's attorney also did not immediately respond to a request for comment.

Cummings wrote that he was bringing forward his request now because special counsel Robert Mueller had asked him to delay acting on the information "until they completed certain investigative steps."

But, according to Cummings, Mueller's directive was dropped after Friday, when Flynn entered into a cooperation agreement with Mueller's team by pleading guilty to lying to the FBI about his conversations with the Russian ambassador to the U.S. at the time, Sergey Kislyak, during the presidential transition. One of those conversations between Flynn and Kislyak was about U.S. sanctions that the Obama administration imposed on Russia in response to Moscow's interference in the presidential election.

A spokesperson for Mueller did not immediately respond to a request for comment.

Mueller's team and congressional investigators have been probing cases in which Flynn may have sought to use his status as Trump's national security adviser for personal financial gain, according to people familiar with the investigation. One such instance, these people said, involves a December 2016 meeting between Flynn and senior Turkish officials to discuss a plot to return a top rival of President Recep Tayyip Erdogan to Turkey and drop federal charges against an Erdogan ally jailed in the U.S. in exchange for $15 million.

Flynn served as an adviser for ACU from April 2015 to June 2016, according to his financial disclosure form. Congressional Democrats have already sought information from Flynn's attorneys about whether he failed to disclose the full nature and extent of his travels to the Middle East during that time, and whether his business interests at that time may have influenced his conduct during what was ultimately a brief tenure as national security adviser.

Flynn later served as an adviser for the IronBridge Group, which was also involved in an Arab nuclear plan. According to a PowerPoint presentation from ACU obtained by Newsweek, Russian firms that would have been involved as well included a Russian arms exporter currently under U.S. sanctions. Reuters reported the project also would have included Rosatom, Russia's state nuclear company, and another Russian engineering and construction firm also under U.S. sanctions.

Federal conflict of interest regulations say that employees should not participate in matters for which they have previously acted as a consultant, or which are likely to have a direct financial benefit for close family.

Cummings conceded that Copson may have lied in his account to the whistleblower, which is why he asked Gowdy to agree to subpoena Copson and others to corroborate the claims.

Subpoenas could not be issued by the committee without Gowdy's approval. In his letter, Cummings noted that when then-Rep. Jason Chaffetz chaired the Oversight Committee he had agreed to seek documents from the White House related to whether Flynn had lied on his security clearance forms about foreign contacts or payments.

But Gowdy, who became chairman after Chaffetz resigned from Congress in June, has not agreed to pursue the issue further, arguing that to do so would potentially conflict with Mueller's probe.

"I believe the American people want Congress to hold President Trump and his Administration accountable, and they are tired of Republicans in Congress putting their heads in the sand," Cummings wrote.

Later Wednesday, Gowdy responded to Cummings with a letter of his own, in which he rejected Cummings’ request to pursue the whistleblower’s claims, citing his continued policy not to “wittingly or unwittingly interfere” with Mueller’s probe. Gowdy said he passed the matter over to the chairman and ranking Democrat on the House Intelligence Committee to determine whether it might be relevant to its investigation of Russian interference in the 2016 election.

“While you may want every Committee of Congress to investigate the same fact patterns, it isn’t a prudent use of resources — something you used to be mindful of,” Gowdy wrote.

Cummings later called it “astonishing” that Gowdy would refuse to meet with the whistleblower, and “resort to desperate jurisdictional excuses to avoid conducting oversight.”