Our party needs a kick in the butt. Sen. Elizabeth Warren (D-Massachusetts), Paul Krugman, and Jon Stewart are currently the standard bearers for that sentiment.

But Bernie Sanders? I just don’t know.

After a career of steadfastly insisting that the Democratic party was not his home, now he wants to not only be a member of the party but its standard bearer? What changed?

Is Bernie’s newfound party affiliation just a practical decision to run in a party that can win rather than risk being a Nader-esque spoiler on a third party line in November? That’s a fair calculation, but doesn’t it wipe away Bernie’s three decades of standing as a principled Socialist?