PRINCETON, NJ -- Mike Huckabee tops a large list of potential GOP presidential candidates in current support for the party's 2012 nomination, with 19% of Republicans saying they are most likely to back him. This gives Huckabee a slight edge over Mitt Romney (15%). Sarah Palin is now at 12% after receiving 16% support in three prior Gallup polls. Newt Gingrich is the only other potential candidate who registers double-digit support. Sixteen percent of Republicans currently have no preference.

The March 18-22 poll of more than 1,000 Republicans and Republican-leaning independents was conducted as the field of candidates has yet to emerge. Since Gallup's February measurement of nomination preferences, Gingrich and Tim Pawlenty have taken formal steps toward announcing their candidacies but have stopped short of doing so. Minnesota Rep. Michele Bachmann is reportedly going to formalize her candidacy by the summer.

There continues to be speculation about the leading candidates' plans. Most political experts believe Romney will eventually enter the race, but questions remain about whether Huckabee and Palin will want to abandon their lucrative media careers to pursue the presidency.

The poll sought to assess how the race might look if either Huckabee or Palin, or both, ultimately do not run, by asking Republicans to name their second and (in some instances) third choices for the nomination. This information was then used to simulate how the candidates would fare under various scenarios.

Romney, Palin Lead if Huckabee Declines to Run

If Huckabee were not a candidate, most of his support would go to the top three remaining candidates. Romney and Palin would essentially tie for the lead, at 19% and 17%, respectively, with Gingrich getting a bump in support to 13%.

Huckabee Strengthens Position With Palin out of Race

Were Huckabee to run but not Palin, his current advantage over Romney would expand to seven points (23% to 16%), compared with the four-point edge he now has with all candidates in the race. Romney's support would essentially be flat with Palin out of the field.

Romney Emerges if Huckabee, Palin Decline to Run

If neither Huckabee nor Palin runs, Romney and Gingrich benefit most, with Romney holding a 22% to 16% edge over Gingrich. No other candidate would receive double-digit support under this scenario, though several minor candidates would get slight increases in their support compared with what it is with all candidates running. Notably, nearly one in four Republicans would have no preference if the field did not include Huckabee and Palin.

In addition to Palin and Huckabee, Donald Trump is another high-profile figure who could enter the race. Though he has said he is only considering running, 1% of poll respondents volunteer his name as their first choice, and enough mention him as a second choice to increase his share to 2% if either Huckabee or Palin do not run.

Implications

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.

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.