With the caucuses only two weeks away, Newt Gingrich’s numbers have collapsed in Iowa and Ron Paul has become the latest GOP presidential candidate to surge to the top, according to a Public Policy Poll released on Monday.

Paul leads the field at 23 percent, followed by Mitt Romney at 20 percent, Newt Gingrich at 14 percent, Rick Santorum at 10 percent, Jon Huntsman, Michele BachmannMichele Marie BachmannYes, condemn Roseanne, but ignoring others is true hypocrisy Bachmann won't run for Franken's Senate seat because she did not hear a 'call from God' Billboard from ‘God’ tells Michele Bachmann not to run for Senate MORE and Rick Perry at 4 percent, and Gary Johnson at 2 percent.

Gingrich peaked in the PPP survey two weeks ago when he led the field at 27 percent, but his support fell to 22 percent the following week and to 14 percent today.

The barrage of campaign ads targeting Gingrich in Iowa and the attacks from his rivals at the GOP debates seem to have also been effective in slashing his favorability numbers in the Hawkeye State.

Two weeks ago, 62 percent said they had a favorable view of the former House Speaker, compared to only 46 percent today. Conversely, those who have a negative view of Gingrich rose from 31 percent to 47 percent over the same period.

In Iowa, traditional wisdom says that a candidate needs a strong ground game to secure voter turnout for the caucus-style election, and some have speculated that even if Gingrich led in the polls on caucus day, his support would be too soft to win.

Gingrich only set up a campaign office in Iowa, this month and previous polls indicated that his supporters were largely open to changing their minds before election day.

Paul, on the other hand, is known for his energized support base and efficient campaign structure. He leads the field in supporter commitment among Iowa voters — 73 percent of those who chose Paul said they had definitively made up their minds.

If Paul’s numbers in Iowa hold through to the Jan. 3 vote, he’ll be the favorite to win the first early-voting state.

Still, there are trouble spots for the Texas congressman.

Two of the groups that are buoying his support in Iowa are younger voters and those who identify as either Democrats or Independents, while Paul comes in a distant third among seniors.

In addition, Iowa voters see Romney as the more electable candidate on the national stage. Twenty-five percent said he has the best chance to defeat President Obama, followed by Gingrich at 17 percent and Paul at 16 percent.

And the Iowa caucuses are notoriously unpredictable, as evidenced by former Arkansas Gov. Mike Huckabee’s unexpected victory in the 2008 contest. With four candidates currently polling in double-digits and two Tea Party favorites still hoping for a surge, nothing is settled.