The House Democrats claim they sent a letter to Mike Pence (head of the Trump Transition Team) in November stating that Flynn had not disclosed that he was serving as an agent of a foreign government, and that this posed a conflict of interest with being national security advisor.
Flynn himself claims he told Pence about this in January.
Pence claims he did not find out about this until March.
The difference? Pence’s timeline clears him of anything but unwitting involvement. But the Democrats kept receipts of the entire transaction, including the reply letter from the Trump Transition Team indicating the letter was received.
Next stop, Paul “Shut Up! Shut Up! No Leaks!” Ryan. Then, President Hatch.