What an inversion last night’s vice presidential debate represented. When Mitt Romney selected Paul Ryan in August, there was a lot of talk about conservatives hoping the man at the top of the ticket would take inspiration and direction from his number two; instead, Ryan has taken a surprisingly low profile in recent weeks, and instead we had the oft-overlooked Joe Biden who was showing his boss the way last night, showing how to bring the fight to the Republicans. Amusingly, conservatives knocked back by Biden’s aggressiveness were quick to note that Obama would be making a big mistake next week if he tried to mimic Biden’s pugnacity. This, of course, is self-evident and beside the point: Obama would never be able to duplicate Uncle Joe, nor would it be in his interest to do so. But there are some specific pointers he could take from him:

1. Talk tax-cut specifics, not tax-cut size. Obama got bogged down in a back and forth with Romney about the size of the tax cuts Romney is proposing—Obama calls it a $5 trillion tax cut, an estimate of the revenue that’ll be lost by cutting rates 20 percent across the board as well as cutting corporate taxes and eliminating the estate tax, as Romney proposes; Romney retorts that it’s not, because that revenue will be made up by (totally unspecified) deduction and loophole closures. Biden fared much better by getting specific about who would be hit and who would be helped by the Romney proposal: he put Ryan on the spot about whether the Romney plan would hit the mortgage-interest deduction for the middle class, and he reminded viewers about the carried-interest loophole—“hedge fund loophole”—that allows Romney to pay such a low tax rate, and that Romney would leave untouched.

2. Link your middle-class roots to the 47 percent. Last week’s debate left many wondering why Obama had not invoked Romney’s 47 percent riff against him. It’s quite possible that the Obama campaign had decided to leave this to Biden, given how well situated he, as a son of Scranton, was to play this card against the Ayn Rand acolyte, Ryan. But Bidens deft use of the 47 percent showed what a strong card is is, and how easy it would’ve been for Obama to slip it in. Here’s Biden:

We knew we had to act for the middle class. We immediately went out and rescued General Motors. We went ahead and made sure that we cut taxes for the middle class. And in addition to that, when that — when that occurred, what did Romney do? Romney said, “No, let Detroit go bankrupt.” We moved in and helped people refinance their homes. Governor Romney said, “No, let foreclosures hit the bottom.”

But it shouldn’t be surprising for a guy who says 47 percent of the American people are unwilling to take responsibility for their own lives. My friend recently in a speech in Washington said “30 percent of the American people are takers.” These people are my mom and dad — the people I grew up with, my neighbors. They pay more effective tax than Governor Romney pays in his federal income tax. They are elderly people who in fact are living off of Social Security. They are veterans and people fighting in Afghanistan right now who are, quote, “not paying any tax.”

I’ve had it up to here with this notion that 47 percent — it’s about time they take some responsibility here. And instead of signing pledges to Grover Norquist not to ask the wealthiest among us to contribute to bring back the middle class, they should be signing a pledge saying to the middle class we’re going to level the playing field; we’re going to give you a fair shot again; we are going to not repeat the mistakes we made in the past by having a different set of rules for Wall Street and Main Street, making sure that we continue to hemorrhage these tax cuts for the super wealthy.

Now, Obama’s not going to get as entertainingly carried away on such a riff as Biden did. But he can make the key point—connecting Romney’s dismissal of the 47 percent to his own family. In the first debate, he did mention his grandmother, the retired bank employee relying on Medicare and Social Security. Why not invoke her as part of the 47 percent—or, for that matter, invoke his single mother, relying on food stamps before she climbed to success as an anthropologist? Placed in this sort of personal context, the riff is even harder for Romney to shrug off.

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