It was clear as soon as Flynn’s indictment was made public on Friday morning that the former national security advisor had flipped. He pleaded guilty to a charge of lying to the FBI later that morning—and now we know why. ABC News’ Brian Ross reports that Flynn has “promised full cooperation to the Mueller team” and is “prepared to testify ... against President Trump, against members of the Trump family, and others in the White House.” He is also prepared to testify that Trump, before his inauguration, “ordered him to make contact with the Russians.” Ross is reporting that Flynn made the decision to flip in the last 24 hours, citing the financial and personal pressure of the Mueller investigation.

Ross, it should be noted, is the only person reporting these details so far (and he has been wrong in the past). But, if true, this is a huge story. Trump has denied, again and again, that his campaign had any contact with the Russians—and whenever contact has been disclosed, he’s adamantly denied all knowledge of it. If Flynn testifies that Trump himself ordered contact with the Russians before the inauguration, that could mean one of two things: If it was before the election, that would indicate collusion with a foreign government to interfere in a U.S. election; if it was after the election, it could be a violation of the Logan Act, which bars citizens from negotiating with foreign governments in a dispute with the United States. Either way, we’re looking at impeachment, and the possible end of Trump’s presidency.

Update: ABC News has issued a “clarification” to Ross’s report saying that Trump ordered Flynn to contact the Russians during the transition, not during the campaign. This is in keeping with both the indictment that was made public on Friday morning and a number of other reports.