Your guide to the vice presidential debate

When/where to watch
7 p.m., CBS, NBC, ABC, Fox, PBS, CNN, Fox News, MSNBC, BBC America, Telemundo. Delaware Sen. Joe Biden and Alaska Gov. Sarah Palin from Washington University in St. Louis. Challenges
joe biden

Challenges

JOE BIDEN
Sounding inoffensive: The garrulous and gaffe-prone Biden must be mindful his opponent is a woman. He must strike a tone neither too condescending nor too deferential.

Showing blue-collar roots: "So long as he's not Joe Biden, Senate Foreign Relations chair, and is Joey from Scranton, the better for the ticket," Democratic strategist Chris Lehane said.

Thinking before he speaks: He'll have to keep his brain ahead of his sometimes too-quick mouth.

SARAH PALIN
Sounding authoritative: Palin has seen her early popularity ebb under a cascade of probing news stories and halting television interviews. Her multipart interview with CBS anchor Katie Couric prompted even some conservatives to question her readiness.

Sticking to her message: "Don't answer the question you were asked, answer the question you wish you were asked, with generalities," said former Yale debater Aaron Zelinsky, founder of presidentialdebateblog.com. Recent gaffes
joe biden

History lesson, anyone?
JOE BIDEN

Bungling history: Biden bungled the history of the Great Depression, saying President Franklin Roosevelt went on TV after the stock market crash to buck up people's spirits. Herbert Hoover was president at the time of the crash, and commercial TV hadn't started.

Too humble, perhaps: He recently said Hillary Clinton might have made a better running mate for Barack Obama.

SARAH PALIN
A reader: Asked what magazines and newspapers she usually reads, she said, "all of them," naming no specifics.

The which doctrine? In an interview with ABC's Charlie Gibson, asked about the Bush Doctrine, she didn't seem to know what it was, responding, "In what respect, Charlie? ... His world view?"

Overstating russian links: "It's Alaska. It's just right over the border."