However, it's worth noting that this is probably a problem that will take care of itself over the next year or so. Nothing will change for most Republican pols: they don't want Palin as at the top of the ticket, but they also don't want to risk attacking her and then facing angry primary voters. But for those running for president, the situation is a bit different. Right now, it makes little sense for them to attack -- Palin may wind up dropping out of the race before Iowa, or she may just fail to rally support above the 20% or so level she's at now. If, however, she looks like a formidable candidate for the nomination by next fall (give or take a few months), then attacking her makes more and more sense.
Of course, these things are tricky in multicandidate primaries. It's true that, say, Mitt Romney will want Tim Pawlenty to be the one to attack the Sage of Wasilla, while Pawlenty will want Mike Pence to do the dirty work. Still, at some point, odds are that one or more candidate will find it in his self-interest to attack. Who? Either the candidate running second to Palin overall (better to risk falling to fifth than to accept finishing second, which is worthless), or a candidate who is doing fairly well and believes he stands to inherit Palin's voters.
Such calculations are tricky to make in advance, and as long as there's a good chance Palin won't be running or won't have a chance to win by January
(Date corrected above)