The snap polls delivered a mixed verdict on last night’s debate. CBS found a sizable win for Joe Biden among undecided voters, while CNN found a much smaller edge for Paul Ryan among all voters. A number of liberal commentators believe Biden’s performance will energize Dems because he went after Ryan so hard.

That’s probably right. But the main reason it was a good night for Dems is a simple one: Biden mounted an aggressive, spirited, and effective defense of the administration’s economic record, and tied it to the larger set of messages that had been working so well against Mitt Romney before Obama’s debate performance clouded the picture.

Biden’s performance may not do much more than stop the Obama ticket’s bleeding, since vice presidential debates are historically unimportant to the outcome. But if Obama picks up where Biden left off when he faces Romney next time, he might be able to stall or reverse whatever momentum Romney continues to enjoy.

In one of the most important exchanges, Biden recapped the history of the last four years, reminding viewers that the economy was in free fall when Obama took office. He reminded them that the administration acted aggressively to save the auto industry, even as Romney adamantly opposed Obama’s bailout (hello, Ohio). Crucially, Biden tied this aggressive defense of government activism to Romney’s “47 percent” remarks, and repeatedly hit the idea that Obama/Biden believe in action to help the middle class, while Romney/Ryan policies would benefit the wealthy with no guarantee that they’d do anything concrete to shore up middle class economic security.

Biden pushed back hard on Ryan’s repeated claims that things are getting worse, something Obama did not do effectively. He repeatedly referenced the 5.2 million jobs created on Obama’s watch and offered a forward-looking message, noting that in an Obama second term, the administration would pass jobs legislation, would pass a middle class tax cut, and would offer more relief to homeowners (an area where the administration has fallen short). On Medicare, Biden drew a sharp contrast between the two sides’ plans — preserving its core mission versus transforming it over time — warning voters: “Folks, follow your instincts on this one.”

In other words, the specifics of Biden’s message were synthesized within a larger story about which side really believes in a strong safety net and concrete, collective action to help those who need it — displaying storytelling skills that deserted Obama during the last debate.

Biden succeeded where Obama failed. But this will only get the Dem ticket so far. As Howard Fineman notes, it’s now up to Obama to rediscover his own voice as he tells the story Biden told last night.

* Biden spoke to middle class: John Dickerson has a very nice take on the debate, noting that Biden relentlessly emphasized protecting the middle class throughout. This is key:

Biden was defending the middle class, while Ryan was defending Romney...Biden’s greatest asset was his passion. Though he might have been over the top, it was possible for a viewer to conclude that he was simply passionate about the middle class.

There is a lot of pundit tsk-tsking this morning about Biden’s rudeness and his laughing. This will likely prove one of those times when the American people don’t follow the punditry’s script.

* About that Biden laugh: Joan Walsh mocks the obsessing over it:

Joe Biden wiped the floor with Paul Ryan at Thursday night’s debate, but we might have to spend a day debating whether he laughed too much while doing it.

* Biden reinforced Dem messaging about Romney: E.J. Dionne makes a key point:

Some will no doubt write that Biden was too hot and overreacted to Obama’s disengagement. But this misreads the net impact of the debate, which was to renew the doubts about Romney, Ryan and their approach that were hurting the GOP before the last debate. Biden stayed on Romney’s class bias from the beginning to the end — he was not shy, as Obama was, about mentioning Romney’s 47 percent comments. A Romney presidency, Biden said, would concentrate on “taking care only of the wealthy.”

If one of Biden’s tasks was to reinforce and revive the messaging that had been working so well against Romney before Obama’s bad debate performance, he may have succeeded.

* Obama Web video hits Ryan debate performance: The Obama campaign is out with a new Web video recapping some of the low points in Ryan’s performance, from the Medicare distortions to the evasions on Romney’s tax plan. (fixed)

The video suggests Dems are likely to seize on Ryan’s pause, after being asked whether women should be worried about abortion remaining legal under a Romney presidency, as a key moment for their continuing efforts to re-expand the gender gap.

* Biden debate performance could revive Dem enthusiasm: As Nate Silver notes, one potential driver of Romney’s poll surge may be the lopsided enthusiasm gap that opened up after Romney’s debate performance, which means Biden’s showing yesterday may blunt Romney’s momentum by bringing Dem enthusiasm back into balance.

* Ryan misleads on Obamacare, Iran, Medicare: CNN does a nice job taking apart Ryan’s claim yesterday that 20 million people are projected to lose insurance due to the health law. Glenn Kessler also finds fault with this and other Ryan distortions on Iran and and Medicare, though he sees plenty of exaggerations and distortions on Biden’s side, too.

* Obama’s strategic ad spending: Reid Wilson has an interesting and fine grained look at how the Obama team is placing ads in ways designed to distract the Romney team from spending where it needs to most. Key point: “So far, the Obama campaign has refused to give up on any battleground states.” By contrast, the Romney team tried to put Michigan and Pennsylvania in play, but have dropped that idea.

* And if Romney wins, GOP will say its ideas were vindicated: Paul Krugman notes that if Romney wins, Republicans will say that it vindicates their doctrine that gutting govermnent is the way to create prosperity, again underscoring how high the stakes are in this election:

Republicans, however, are committed to an economic doctrine that has proved false, indeed disastrous, in other countries....The party remains opposed to effective financial regulation despite the catastrophe of 2008; it remains obsessed with the dangers of inflation despite years of false alarms. So it’s not likely to give up its politically convenient views about job creation....In other words, politically good things may be about to happen to very bad ideas. And if that’s how it plays out, the American people will pay the price.

And if the economy continues to improve next year, it will only be seized upon as further proof that Republicans were right all along.

What else?