Congressman Ron Paul (R-TX), once labeled nothing more than a "gadfly" by a former Bush strategist, has emerged as the GOP's leading candidate in the crucial Iowa caucuses, the first post-Christmas poll to be published this year has found.

With the nation's first primary vote just six days away, Paul is leading former Massachusetts Governor Mitt Romney (R) 24 percent to 20 percent, according to the democratic-affiliated Public Policy Polling (PPP) group.

The same survey also found that former House Speaker Newt Gingrich (R-GA) has sunk dramatically in recent weeks, down to just 13 percent, putting him within the margin of error of other second-tier candidates like Rep. Michelle Bachmann (R-MN) at 11 percent and Texas Governor Rick Perry (R) at 10 percent.

Former Senator Rick Santorum (R-PA) was tied with Perry at 10 percent, followed by former ambassador Jon Huntsman (R) at 4 percent and former Louisiana Governor Buddy Roemer (R) at 2 percent.

The poll found that while Paul leads the pack, he does so thanks to a broad coalition of voters, not all of whom are actually Republicans. PPP found that about one-fourth of Paul's supporters are either independents or Democrats who plan to cross over and support him in the Republican primary, giving him the crucial edge over Romney who otherwise holds a narrow lead among Republicans.

PPP also found that Paul is pulling much greater support from younger voters, who he wins over Romney by a margin of 35 percent to 11 percent. He's also got an edge when it comes to how committed his supporters are: 77 percent are "firmly committed" to him, while Romney's core support is at 71 percent who are firmly committed.

Finally, in potentially the most crucial campaign metric, Romney seems to be losing momentum where Paul is gaining. PPP found that Romney's favorability rating has dropped into negative territory for the first time in months, going from 49 percent favorable and 40 unfavorable -- a 9 percent rating -- to 44 percent favorable and 47 percent unfavorable --a -3 favorability rating.

PPP concluded that if Paul can maintain his ground game and bring in younger voters to next week's caucuses, "he'll win," but they warned: "If turnout ends up looking a little bit more traditional, Romney will probably prevail."