UPDATE 3: Rep. Gowdy replied to Rep. Cummings confirming he is not interested.
Gowdy says he forwarded Cummings' letter to House Intelligence Committee leadership so they can pursue the lead if they so desire.
UPDATE 2: CNN's Manu Raju:
Gowdy on whether House Oversight will look into Flynn issue raised by whistleblower. "I do get that Democrats want every committee in Congress to be investigating the same fact pattern. I don't think that's the best use of our resources." https://t.co/XyQ6Gi8oyr
— Manu Raju (@mkraju) December 7, 2017
UPDATE: Business Insider's Natasha Bertrand:
Just in: Statement from the lawyer for Alex Copson, who purportedly told the whistleblower that Flynn said Russia sanctions would be "ripped up." Lawyer says no member of ACU (where Copson is managing director) ever "received communication" from Flynn.
Former national security advisor Michael Flynn allegedly texted a business associate on Inauguration Day – during President Trump's speech – and gave the go-ahead on a lucrative plan to work with Russia on building and defending nuclear reactors in the Middle East.
This explosive information comes via a whistleblower who has approached Representative Elijah Cummings (D-MD), the ranking Democrat on the House Oversight and Government Reform Committee.
Rep. Cummings has sent a letter to committee chairman Rep. Trey Gowdy (R-SC), detailing the whistleblower's account, deeming it credible, and requesting a complete, bipartisan investigation.
The unidentified whistleblower says he had a conversation on Inauguration Day with Alex Copson, managing partner of ACU Strategic Partners. Copson and Flynn were working together on the joint nuclear reactor project with Russia.
After sharing the whistleblower's information, Cummings proceeds to explain how Gowdy has been stonewalling efforts to pursue this substantive lead by disregarding evidence; refusing to allow the committee to vote on White House subpoenas; declining requests for witnesses to produce documents and appear for interviews; and claiming a desire not to interfere with the special counsel's ongoing investigation.
Cummings points out this last excuse directly contradicts Gowdy's daily participation in the Russia probe as a member of the House Intelligence Committee and his previous dogged pursuit of information as Chairman of the Benghazi Select Committee.
Cummings...said the whistleblower approached the committee in June, but Mueller's investigators asked him to "hold on the public release of this information until they completed certain investigative steps."
"They have now informed us that they have done so," Cummings told Gowdy, who did not immediately respond to a request for comment.
Flynn Said Russian Sanctions Would be ‘Ripped Up,’ Whistle-Blower Says (NYT)
Flynn texted partners about nuclear plan during inauguration, whistleblower says (Politico)