Electability.
That doesn’t explain why you think Ron Paul is getting those votes. And I think Bachmann is the only one with serious electability questions among those 4. Palin was unfairly treated, but her gaffes were so played up by the media that I think she would have less electability than Newt, Perry or Santorum. She could recover in a campaign, but only if she never made anything like the same kind of gaffes. I haven’t seen her layer on enough depth on the issues in her various interviews since she left the governorship to make me believe she would be able to avoid the same traps. She knows the conservative theology inside and out but doesn’t seem to have the ability to link it to specific real-world examples and make it relevant to people’s lives.