Warren is off-the-cuff, free-wheeling and direct in all the ways Clinton is cautious and rehearsed. But it is a reinforcing rather than an invidious contrast and likely helps bring to the surface Hillary's progressive background that has been buried by decades at the pinnacle of Democratic party politics and years as the punching bag of the left of the party which feels excluded by the seemingly endless Clinton ascendency.

It may sound crazy to attach so much to her recent Twitter contretemps with Donald Trump. But the tone, rhythm and style are exactly what the Democrats need to knock Trump down and bring out his toxic mix of personal insecurity and emotional instability. It's not over-earnest or off-key or droning (traditional Democratic tonalities - let's be honest). She's mocking, substantive and constantly on target.
Indeed, Trump's responses to Warren, his attacks on her, make it clear to me he'll have a hard time handling her.

My one concern, though I wouldn't say it is a major one, is what I talked about almost a year ago, which is the fact that he moves so quickly, is so protean that he can just rapidly get in the spokes of a conventional campaign. And any Hillary Clinton campaign is highly, highly conventional. Even though Warren is so different from Trump's mix of hatred, bombast and lurking violence, I think Warren can match Trump on this ability to cut free from the media vectors and planning supply lines of the modern presidential campaign and strike hard and fast in real time. That's a big deal.