The GOP's attitude is that she's an annoying insect who probably can't win the election, but they'll back the only horse they have in that race, if not entirely graciously. The 'real' Republican she beat in the primary refused to endorse her. She's a (former?) Fox News employee and Tea Party darling, but she's a radical nutbag, and the party knows it.
Frankly, I think a lot of the GOP insiders would love to see her -- and most of the Palin and Tea Party candidates -- get beaten like a bag of rented chumps. In the first place, they want to obstruct Obama, not steer him, since they don't want get blamed for being in charge during these ugly times. Beyond that, it's so much easier to sabotage and then lay blame than to actually fix things. If the Teabaggers get into office in a big way, then suddenly the GOP will be expected to get big results, which is difficult at best and probably unrealistic.
In the second place, these people aren't much more popular with the mainline Republicans than they are with anyone else. The Teabaggers attack the GOP mainstays much more viciously than the Dems would ever have the backbone for. And they're hard to control and have unworkable goals. They're no one's friends, really. And for similar reasons, not many people in the GOP are big fans of Sarah Palin, either. Every time she endorses some juicebag who fails to get elected, there are as many GOP senators celebrating as Democrat, I guarantee it.