This must-watch clip of Elizabeth Warren aggressively rebutting the GOP’s “class warfare” charge is burning up the internet, and once you watch it, you’ll understand why:

Warren’s camp tells me the event took place in Andover, Massachusetts last month, and you can read the transcript over on Atrios’s blog. The gist is that Warren rebuts the charge that asking the rich to pay a little more in taxes is “class warfare” by pointing out that no one grew rich in America in isolation.

As Steve Benen rightly notes, very few Democrats are able to make the basic case for the social contract quite this effectively. And this is coming from someone who only started campaigning seriously a few weeks ago. So she may have lots of room to grow.

Here’s why I think this video is so important. As I wrote the other day, a Warren candidacy could test the electoral limits of true populism in a way that few other Dems have been willing to venture. Here we’re seeing the beginnings of this — this is a candidate who is starting out with her own voice.

Republicans are planning to paint Warren as a liberal Harvard elitist — they’re already referring to her as “Professor Warren” — in order to make it tougher for her to win over the kind of blue collar whites from places like South Boston that helped power Scott Brown’s upset victory.

But as this video shows, Warren is very good at making the case for progressive economics in simple, down-to-earth terms. Despite her professorial background, she sounds like she’s telling a story. She came across as unapologetic and authorative, without a hint of the sort of defensiveness you hear so often from other Democrats when they talk about issues involving taxation and economic fairness. This is exactly what national Dems like about Warren.

For all I know, Republicans may be able to use her embrace of high end tax hikes and other Obama policies, her bio (she comes from out of state) and her day job to persuade blue collar whites she’s just another pointy-headed tax-and-spend liberal. But this video suggests it isn’t going to be so easy to do that. This contest could be the ultimate test of whether such voters can be won back through unadorned and unabashed class-based populism.

This is going to be one heck of a Senate race.

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