Former House Speaker Newt Gingrich leads the Republican race in Iowa with 33 percent support in a new Washington Post-ABC News poll, with Mitt Romney and Ron Paul trailing at 18 percent apiece. Digging into the poll data among all potential caucus participants reveals distinct constituencies for each of the three top Hawkeye state contenders.

The following are based on all potential GOP caucus-goers, not just the smaller number most apt to attend. This allows for broader sub-group analysis. Among this larger group, the overall results are Gingrich 28 percent, Romney 18 percent and Paul 16.

Gingrich - The former speaker earns higher support among men than women (33 vs. 24 percent), performs particularly well among those aged 40 and up (33 percent), while he struggles among younger voters (18 percent). Gingrich boasts a wide lead among conservative voters, who made up a hearty 88 percent of all 2008 caucus-goers, but he performs less well among moderate and liberal Republicans.

More than four in 10 strong tea party supporters pick Gingrich as their top choice in the new poll, compared with fewer than half as many potential caucus-goers who oppose the movement.

Romney and Paul after the break...

Romney - Romney’s support is highest among moderate and liberal Republicans, where he earns 25 percent; he also breaks 20 percent among tea party opponents and weak supporters of the movement. His weak points include “very conservative” caucus-goers and strong tea party supporters, among whom he draws 10 percent support.

Paul - Paul scores big among the (relatively) young, winning nearly three in 10 of potential caucus-goers under age 40. He fares slightly better among men than women, but runs fairly evenly across ideological groups as well as supporters and opponents of the tea party movement.

Paul holds another advantage: strong commitment. Fully 50 percent of his supporters say they’ll definitely support him on caucus night, higher than 37 percent of Gingrich’s supporters and 28 percent of Romney backers who are fully committed.

The poll was conducted Nov. 30 to Dec. 4, among a random sample of 858 potential Iowa Republican caucus-goers, including 356 most likely to participate. Interviews were conducted on conventional landline and cellular telephones.The margin of sampling error for potential voters is plus or minus four percentage points; it is six points for likely voters.

Read the full poll results

Sign up for Post Polling e-mails

Follow Post polling on Twitter

Like Post Politics on Facebook