It's important to remember that a nationally televised debate is important for its effect on the 20% or so of voters who are persuadable. It doesn't matter that, as one poll recently suggested, 33% of voters say that Palin makes them "less likely" to vote for McCain -- going from "snowball's chance in hell" to "iceberg's chance" is not important to the campaign at this stage.
Palin's main job on the campaign from here on in is energizing conservatives who are unenthused about McCain --and thus improving the turnout among that group on election day. Tonight's debate is not really the forum for that; she'll get it done more effectively through live rallies and interviews on conservative talk shows.
VP selections rarely make anyone vote for a ticket; they occasionally convince people to vote against it -- hence the oft-repeated maxim to "first do no harm" with the VP pick. McCain took a chance that he could confound this rule, and the risk has failed. Some number of those persuadable voters who might otherwise be convinced to vote for McCain are now reluctant to, because A) they genuinely fear a potential Palin Presidency, and/or B) they think that the Palin selection demonstrates an atrocious lack of judgment for McCain.
Thus, Palin's task tonight is two-fold. First, convince that group of people that she's really not so awful. Second, re-focus people on the more important reasons that they should want to vote for McCain over Obama.
The second task is relatively straightforward: she needs to repeatedly tell people that Obama and Biden are typical tax-and-spend liberals, who will inevitably raise your taxes, destroy jobs, and increase the national debt. (The other argument, that Obama is too inexperienced and naive to be trusted with national security, is obviously best left to McCain.)
For the first task, Palin needs to accept and move beyond her obvious lack of knowledge about national and international policy. She can't fake her way through it, and is a disaster when she tries.
Instead, she needs to inform people of how she has stepped into new tasks before, and learned them quickly and adeptly. She can do this without literally saying "I knew nothing about the Alaska Oil & Gas Commission when I was named chair, and I would have sounded like an imbecile if I was interviewed about it before I started." But she can describe how as chair she became so adept at its workings that she was able to identify and expose the former attorney general's conflict of interest in negotiating a coal exporting trade agreement. People will get it. She should be able to tell stories that illustrate her quickly-learned skills as governor, whether working legislation through, or making changes within departments and agencies.
If I was advising her, I would tell her that when she feels stumped on an issue, she should admit it and move on. For example, here's what she could have done with Katie Couric's question about Supreme Court decisions:
You know, I'm not comfortable talking just yet about specifics of federal law and jurisprudence -- obviously I have plenty of opinions, but like most people I don't feel well-versed on the groundings in Constitutional law, to have a public conversation about it. What I can tell you is that as a general philosophy I believe in a fairly strict reading of the powers enumerated in the text, rather than trying to squeeze more and more federal authority into a broad interpretation of the language. I suppose that comes from being a public official in an independent-minded state like Alaska -- we tend to think that we can find solutions that fit our needs, rather than take one-size-fits-all direction from Washington. That's the liberal approach that Barack Obama and Joe Biden tend to take, that we in Washington are going to make the rules for you in Georgia and Minnesota and Alaska. And it's why we keep getting more and more big national programs that require more of our tax dollars, to do things that I believe we can do better and more efficiently at the state and local level.
Sure, the elitists will mock you for wanting to be a heartbeat away from the Presidency without knowing anything about the Constitution. But those persuadables -- particularly the ones likely to lean toward McCain -- will come away thinking about how Obama/Biden plan to keep expanding the size of the federal government, not about Palin admitting her ignorance.