There are some things about american demographics I think will prevent the poll numbers from coming to fruition.

Clinton being a woman, and the current make up of society and how we still don't give women equal treatment in the work place. Since we can't seem to do that, why would America vote to give a woman the top job? I think there is still a fundamental equality problem to be contended with before it will actually happen.

Obama being non-white (cause he sure isn't African American) will have to overcome the overwhelming racial cravas currently prevalent in America. Could he get elected? Perhaps, but the high probability of him being assassinated would probably prevent him from actually accomplishing what he has set out to do. So I don't think Americans will vote him into office by popular vote.

Edwards has a good chance to actually get into office, but his coffers are not as deep as Clinton or Obama, and so doesn't have the media attention needed to overcome them as a primary democratic nominee.

To the original question: Do the republicans have someone that could beat out any of those three? Yes, Ron Paul, but his voter popularity has been hampered by lack of media attention. He is the only one of the republicans that is for a real shift in republican policy. The others are more for continuing the Bush status quo, and even Clinton has been accused of this direction problem.

Americans are tired of the status quo, and in order to succefully get someone into office, the person who becomes the primary nominee is going to need to be the voice of that change, and also have a realistic chance of staying in office to make that change for Americans to consider them for their vote.

The side notion to consider, is that Americans are so sheepish to the media attention thrust onto them, that whom ever the media says is the front runner, that is who they would vote for, so long as it was their party.