A University of Iowa poll released Monday shows that Mitt Romney continues to be the leading GOP presidential candidate among likely voters in that state's first-in-the-nation party caucuses on Jan. 3.

Among Democrats, Sen. Hillary Clinton of New York is the favorite, according to the poll, closely followed by Sen. Barack Obama of Illinois. Support for the party's vice-presidential nominee in 2004, former Sen. John Edwards of North Carolina, is slipping.

The Hawkeye Poll is a random sample of likely caucus-goers and was conducted Oct. 17-24. The survey questioned 285 Republicans, with a margin of error of 5.8 percent, and 306 Democrats, with a margin of error of 5.5 percent.

The poll found that Romney's lead has continued to grow since March. Romney, who headed the successful 2002 Winter Olympics in Salt Lake City, had the support of 36.2 percent of likely GOP voters in the latest poll, up from 27.8 percent in August and 16.9 percent in March.

"It's clear Romney is the one to beat in Iowa," said David Redlawsk, Hawkeye Poll director and a political science professor at the University of Iowa. "His support is now nearly triple his nearest competitor. He leads among all demographic groups, including religious conservatives, and is especially strong among the older voters, who tend to be most likely to attend a caucus."

But former Arkansas Gov. Mike Huckabee is gaining in the poll and is "developing a following among evangelical Christians, which may allow him to make a strong showing at the caucus," Redlawsk said.

Romney's campaign workers said they are getting ready for a closer race.

"Governor Romney is pleased with the progress we have made in Iowa so far," said his campaign spokeswoman, Gail Gitcho. "However, we fully expect the race in Iowa to tighten over the next two months, and we will continue to run like we are 10 points behind — taking nothing for granted."

Gitcho said the poll results show Romney's "message of conservative change in Washington is resonating."

Romney, who served as governor of Massachusetts after leaving Utah in 2002, has invested heavily in Iowa to build name recognition. The Midwestern state is seen as key to the presidential race, because Iowa is the first to vote for party nominees.

Key, too, for Romney is how he will do with evangelical voters, some of whom have questioned his membership in The Church of Jesus Christ of Latter-day Saints, as well as his recently changed positions on abortion and other so-called values issues.