What You Need to Know About Tonight's Debate

The political world is holding its breath in anticipation of tonight's potentially pivotal presidential debate. Here's what you should know going in:

• Who are you again? Barack Obama and Mitt Romney have been saying each others' names for months, but they haven't actually spent any time face-to-face. "The chemistry between the two candidates cannot be rehearsed," the New York Times observes, and it could be crucial.
• Stagecraft: Everything else, however, has been rehearsed—the candidates have even agreed on such details as how many family members can come onstage after the debate.

• Which Romney? The challenger is getting conflicting advice about how he should approach the debate, Politico reports, with some urging him to attack, and others worrying that he'll put off voters if he charges too hard, given Obama's high personal approval rating. One senior adviser tells the Times that in rehearsal he's shot for "respectfully aggressive."
• Will Obama go negative? Obama faces a similar problem, Politico points out; his lead is based on a summer of relentless attacks on Romney. Can he keep attacking him to his face without endangering those personal approval ratings?
• Libya is domestic, right? This debate is supposed to focus on domestic issues, but Romney advisers tell the Times they want to bring up Obama's response to the Benghazi embassy attack.
• It's the economy, mostly: But the main issue of the debate will be the economy. We can guarantee this, because the first three of the debate's six 15-minute segments are titled The Economy I, The Economy II, and The Economy III, the AP reports.
• Just the facts: Both candidates have had some trouble telling the truth this cycle, so the Times has run a kind of pre-fact check on the debate, listing claims the candidates are likely to make on debt, taxes, and Medicare, and how to evaluate them.
• Tie goes to the challenger: In good news for Mitt Romney, the first debate has a statistically significant history of helping the challenger, Nate Silver finds.
• No time for romance: If Michelle Obama looks less than happy tonight, there's good reason: Today is the Obamas' 20th wedding anniversary, the AP points out. "Go figure," the first lady said in a recent interview.

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