The truth behind the numbers: Pre-fact-checking the VP debate

Last week's presidential debate impacted the race more than most voters expected. After his lackluster performance, President Barack Obama's lead has shrunk and Mitt Romney's campaign has been reinvigorated.

So, Thursday night's debate between Vice President Joe Biden and Republican vice presidential nominee Paul Ryan matters more than most debates between potential vice presidents past. While Biden has a chance to do some damage control and stall the Romney-Ryan surge, Ryan will press for further gains.

At Centre College in Danville, Ky., at 9 p.m. ET, Biden and Ryan will tangle on issues including health care, the national debt and taxes. In other words, things might get wonky. Here's a guide to some of what you might hear, with the spin fact-checked in advance.

Taxes

Ryan: Ryan is likely to pounce on a recent Biden sound bite featuring the vice president saying the Romney-Ryan tax plan would crush the middle class, which has been "buried for the past four years."

Out of context, it sounds like Biden is arguing that the Obama administration has actively hampered the middle class with taxes rather than helped to revive it. The Romney campaign has been running ads suggesting as much, and Ryan is probably aching to use the "buried" line against his opponent as he pitches a very different tax plan.

But a viewing of the whole clip delivers a different message: Biden was complaining that Bush-era taxes sparked the Great Recession by favoring the wealthy and burdening middle-income Americans.

In short: Biden was arguing that negative effects of the Bush tax cuts have lingered the past four years, and further warning that the Romney-Ryan plan is more of a losing formula.

Biden: But is Biden himself being truthful in his original remark? Will Romney and Ryan favor the rich and pressure the middle class?

Before either candidate muddies this up, here are the key planks of the Romney-Ryan tax plan:

- Bush-era income tax cuts and capital gains tax cuts become permanent.

- All income tax rates are cut by an additional 20 percent.

- The Alternative Minimum Tax and the estate tax are repealed.

In order to balance these cuts and make a plan that's "revenue-neutral," Ryan will stress that his ticket plans to strip the tax code of myriad loopholes and deductions.

On this issue, the vice presidential nominees will be cleaning up some unfinished business from the presidential debate last week when Obama frequently dropped the "$5 trillion" figure in reference to Romney's tax cuts for high-income citizens.

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The president is getting that number from a study by the Tax Policy Center, which wrote that until Romney specifies which loopholes and deductions are on the chopping block, the plan doesn't add up to be revenue-neutral. The suggestion is that Romney will have to raise taxes on the middle class in order to fund his initial slash across the board.

Watch Ryan try to talk around this on Fox News recently.

As the Washington Post notes, Romney and Ryan like to say that "six other studies" debunk the TPC study and back their math. But that's not true, not yet.

Social Security

Biden: All this tax talk will bleed into Social Security. Biden is likely to repeat his charge from the campaign trail that under the Republicans' tax plan, seniors will have to pay "$460 a year more in taxes for their Social Security."

Biden's getting ahead of himself here, taking advantage of his opponent's vague plan by offering an especially dreary prediction of its effects.

PolitiFact.com observes that the "$460 a year" line is one of many ways to complete the math of the Romney-Ryan tax plan, though, "it's at odds with what Romney has said he'll do, which is to protect deductions for the middle class and not raise taxes."

The Debt

Ryan: The national debt is Ryan's pearl, and you can expect him to hammer Biden on the administration's contribution to America's ballooning deficits.

Pro-Republican ads allege Obama added $5 trillion to the debt in his first term alone. Ryan is likely to follow their lead on characterizing the scope and depth of the administration's contributions, whether he cites that specific figure or not.

But the breakdown of Treasury data from the Congressional Budget Office (courtesy of PolitiFact) informs a very different picture.

If you combine spending increases linked to Obama policies with increases in discretionary spending on his watch, it only adds up to about 43 percent of the three years' worth of deficit, PolitiFact finds.

Of course, there are some other ways to support the GOP line of attack: include Obama's tax cuts and his share of the contribution rises to 56 percent—but would Ryan really want to criticize the administration for lowering taxes?

Medicare

Ryan: Ryan was one of the first to jump-start the GOP's "Medicare raid" meme, which alleges that Obama is about to rob Medicare to the tune of $700 billion, in order to pay for the Affordable Care Act.

In fact, the oft-cited $700 billion figure represents the savings the ACA yields over 10 years by reducing Medicare spending, and it's chiefly the providers rather than beneficiaries who pony up to finance the long-term spending cut.

Ryan tried this out recently at an AARP conference and was met with a storm of jeers. However, the audience in Danville is barred from cheering or booing, so he might have the chance to slip this in his remarks tonight without worrying about vocal backlash.

Biden: Many of Obama's and Biden's attacks on their opponents' plans for Medicare are centered on Ryan's famous 2010 budget, which has undergone considerable revision since its author was absorbed into the Republican ticket. So it's important to separate the critique of the old plan from that of the new plan.

When Biden attacks the "Romney-Ryan plan" on Medicare, claiming it costs seniors an extra $6,400 a year, he's attacking Ryan's old plan. FactCheck.org notes that seniors on private plans under that budget would pay more than they would under traditional Medicare, somewhere around another $6,000.

However, unlike that plan—in which the growing spending on subsidies skidded to the rate of inflation— the new plan stipulates that premium support would always be enough to cover the two cheapest plans in the market.

At the moment, according to the CBO, it remains unclear whether or not the new plan would incur greater costs to beneficiaries, and to what degree.