Potential 2012 Republican presidential primary voters remain torn between Sarah Palin, Newt Gingrich, Mitt Romney and Mike Huckabee, according to a new Public Policy Polling survey.

But voters' second choices, should their favorites opt not to run, offers an interesting glimpse of which pockets of the GOP the candidates must compete for.

-If Gingrich opts not to run Huckabee would pick up 31 percent of his supporters, while 27 percent said they would gravitate to Romney and only 19 percent to Palin.

-If Huckabee stays on the sidelines it helps Palin's chances. She's the second choice of 34 percent of his supporters, while Gingrich and Romney take 19 percent and 17 percent respectively.

-Inversely, if Palin doesn't run, Huckabee benefits. Almost a quarter of Palin supporters said the former Arkansas governor is their second choice, followed by 20 percent who named Gingrich and 12 percent who picked Romney.

-Should Romney decide not to run, it helps Palin. She's the second choice of 27 percent of Romney supporters, Huckabee took 23 percent of Romney's supporters and 14 percent said they would go for Gingrich.

The PPP poll of 400 typical national GOP primary voters was conducted Nov. 19-21 and had a margin of error of plus or minus 4.9 percent.