The tribal resentment problem is a powerful metaphor.  But it is important to recognize the yinyang problem - that the Republicans have nearly monopolized the male side of the wholistic Chinese metaphor without having to say much of anything about the female side of the equation.
What makes Palin a brilliant choice is her now trademark metaphor - the pit bull with lipstick.  She spits out male get tough metaphors like Annie Oakley with a pump-action shotgun.

Democrats - John Kennedy the prime example - once had a get tough side that was a product of FDR's wartime leadership and the WWII national unity that was still recent memory.  Vietnam took that away from the Democrats and we have not recovered.
JFK, running against Nixon a Red-baiter with no military credential, not only had the dubious Missile Gap, but a new war fighting strategy - fighting guerillas and "brush fire wars".The Green Berets and the Peace Corps were Kennedy's and both were products of the same missionary spirit.
All this to say that what Barack Obama lacks is not a foreign policy but a military policy.  If he does not find a way to show that he has one, that it has strength, that it is forward looking, and that he is the one who really will chase Bin Laden to the gates of hell Obama and the Democrats will not win this election.
- GWC