Former national security adviser Michael Flynn promised a business associate before the inauguration of Donald Trump that U.S. sanctions with Russia would be "ripped up" by the incoming administration, according to a witness account described by House Democrats.

Elijah Cummings, the top Democrat on the House Oversight and Government Reform Committee, said Wednesday that the whistle-blower described how within minutes of Trump being sworn in, Flynn texted a former business colleague saying they were "good to go" with a plan to work with Russia on building Middle East nuclear reactors.

Cummings detailed the whistle-blower's account in a letter to House Oversight Chairman Trey Gowdy, saying the witness came forward in June and that he has now been authorized to share his account publicly.