Washington (CNN) How much legal peril is President Donald Trump actually in? That's the $1 million question as special counsel Robert Mueller continues to probe Russia's involvement in the 2016 campaign and potential collusion between the foreign power and Trump's presidential team. Trump lawyer John Dowd threw a grenade into that thicket of legal issues earlier this week when he asserted that the President simply cannot obstruct justice.

So, where is all of this going? And how does the legal track being pursued by Mueller jibe -- or not -- with the political end of the investigation? The New Yorker's Jeffrey Toobin gets into all of that (and more!) in his new piece entitled: "Michael Flynn's Guilty Plea Sends Donald Trump's Lawyers Scrambling."

I reached out to Jeff, who is also a CNN contributor, to talk more about his piece and make a few predictions about where the Mueller investigation is headed. Our conversation, conducted via email and lightly edited for flow, is below.

Cillizza: You make an important distinction between the legal case against Trump and the political one. Explain.

Toobin: The legal case, if there is one, would be a criminal indictment of the President -- for obstruction of justice or some other crime. There is a very open constitutional question about whether a sitting President can be indicted, that is, whether the courts will allow such a case to proceed while he is in office.

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