Ron Paul’s 2012 campaign continues to gain traction, according to the latest news from Public Policy Polling (PPP).

PPP has him first at 23 percent, Mitt Romney second at 20 percent and Newt Gingrich third at 14 percent among Republican caucus voters surveyed in December.

Gingrich’s share of vote has plunged two weeks in a row; he was at 27 percent, then dropped to 22 percent and now pulls only 14 percent in the latest poll.

“Newt Gingrich's campaign is rapidly imploding, and Ron Paul has now taken the lead in Iowa…Negative ads over the last few weeks have really chipped away at Gingrich's image as being a strong conservative,” said PPP.

Indeed, Gingrich has taken a big hit in his credibility as a principled candidate; only 36 percent think he has strong principles versus 73 percent for Paul and 50 percent for Romney.

Paul, meanwhile, continues to dominate among young voters. For voters under 45, he pulls in 33 percent versus 16 percent for Romney and 11 percent for Gingrich.

Paul also leads by a wide margin among voters who identify themselves as independent, Democratic and “other.” Among those who identify themselves as Republican, Romney leads with 22 percent, followed by Paul with 19 percent and Gingrich with 17 percent.

Ever since Gingrich was vaulted to the top of the polls, Paul’s campaign has aggressively attacked his Republican credentials.

In the video below, it attacked Gingrich for supporting individual mandate for health care, questioning rising GOP star Paul Ryan’s Medicare stance and flip-flopping based on who is paying him.”