And while Romney and Huckabee have been ahead at various times, Palin has never been in the lead.
Currently Huckabee leads Romney but the margins are still close.
Here's an excerpt from Gallup's analysis of the situation:
There is no clear front-runner for the 2012 Republican nomination, which is a departure from what it has been in years prior to a presidential election. Huckabee may be the closest thing to a front-runner at this point, but he has yet to hold a statistically significant lead in any survey. But his candidacy, as well as that of Sarah Palin, is far from assured.Click here for more.
Romney would apparently benefit more from Huckabee's sitting out the race than from Palin's doing so, and he would move to the front of the field (though not by a statistically significant margin) if neither Huckabee nor Palin runs.
All of this underscores the current wide-open nature of the race, which could eventually find some structure in the coming months as the potential candidates make official decisions about entering the race, begin to campaign in earnest, and face each other in a series of scheduled debates starting in May.