"Sarah's the one," said one leading conservative who is convinced McCain will lose this election. "The party is broken and only she can fix it. We need someone who comes from outside Washington and relates to the aspirations of ordinary Americans," he added. Palin appears to be subtly distancing herself from Mr McCain and positioning herself for a presidential run in her own right, much as John Edwards did in 2004 as John Kerry's Democratic vice-presidential running mate.
She has repeatedly stated, often on conservative talk radio, that she would be more aggressive in making the case against Obama while at the same time distancing herself from campaign tactics such as automated telephone calls.
Palin has contradicted McCain on policy towards Pakistan, over drilling for oil in Alaska and on de-listing North Korea as a terrorist state. While some believe these are merely gaffes illustrating her uncertainty over policy, others fear she is deliberately undermining the Republican nominee.
She has also made clear she was unhappy with the way she has been "handled" by the McCain campaign, which kept her out of the media spotlight until it felt she was ready and then arranged a series of interviews with network anchors that turned into disasters.
Some Republicans are concerned that Palin's reputation has been irrevocably damaged among the moderate voters needed to win a general election, and that she is already too divisive a figure.