(Updates with Obama appearance in New Hampshire, new poll)

DES MOINES, Iowa, Dec 19 (Reuters) - Republican Mitt Romney attacked rival Mike Huckabee for criticizing President George W. Bush's foreign policy on Wednesday, while a new poll showed the race among Democrats in Iowa still neck-and-neck.

As candidates revved up their campaigns before a brief Christmas break, some released advertisements evoking the holiday spirit, including one from Republican Rudy Giuliani that featured Santa Claus.

None of the light-hearted spots provoked the criticism that former Arkansas Gov. Huckabee did with a "Merry Christmas" advertisement that included a book shelf behind him that looked like a cross.

Huckabee, a former Baptist preacher seeking support from Christian evangelicals in Iowa, rejected criticism of the ad.

Iowa on Jan. 3 starts the state-by-state process to pick the Democratic and Republican candidates who will face off in the presidential election on Nov. 4, 2008.

Romney, who has lost a big lead to Huckabee in the midwestern state, sought to raise doubts about his rival's foreign policy credentials, saying his criticism of Bush's foreign policy was more suitable for a Democrat.

Last week, Huckabee said the Bush administration's "arrogant bunker mentality has been counterproductive at home and abroad" and promised that as president he would reach out to the rest of the world.

"I think Governor Huckabee made a significant error in insulting the president as being subject to an arrogant bunker mentality," Romney said in Davenport, Iowa. "I disagree with that. I think the president is a man who has acted out of a desire to do what is right for America."

Romney, a former Massachusetts governor who said in August he would not be a "carbon copy" of Bush if elected, but has supported his troop build-up in Iraq, wants to peel away conservative Republican voters from Huckabee.

Huckabee has come out of nowhere to lead Republican polls in Iowa and challenge Giuliani for the lead nationally. He defended his words in an MSNBC interview but said he was criticizing the administration, not Bush himself.

"I don't apologize for that because I think that when we're engaged in the world, we need to make sure that even if we call people to join us in a multilateral approach to fighting terrorism, if they don't do it on our terms we don't say that they're with the enemy," Huckabee said.

HUCKABEE, ROMNEY GAIN

A Reuters/Zogby poll released on Wednesday said Huckabee has wiped out an 18-point deficit in one month to pull within one point of Giuliani, 23 percent to 22 percent, nationally, with Romney in third place at 16 percent.

An NBC News/Wall Street Journal poll released on Wednesday, showed Romney gaining nine points in a month to tie Giuliani, who dropped 13 points. The two Republicans were each at 20 percent in that poll, with Huckabee in third place at 17 percent.

Among Democrats, New York Sen. Hillary Clinton's national advantage over Illinois Sen. Barack Obama shrunk slightly to eight points from 11 points last month, according to the Reuters/Zogby poll.

In the NBC/Journal poll, Clinton held her national lead, with the support of 45 percent of Democratic primary voters, compared with 23 percent for Obama.

Campaigning in New Hampshire, which holds its primary on Jan. 8, Obama zeroed in on struggling lower- and middle-class voters by highlighting his plans to ease their tax burden and make health care and college education more affordable.

"There aren't many issues that you are concerned about that I have not worked on," Obama told a high school student at a town hall meeting in Manchester, trying to convince her to cast her first vote for him.

While Clinton leads nationally, all eyes are on a tight race in Iowa between her, Obama and former North Carolina Sen. John Edwards. A Washington Post-ABC News poll said 33 percent of Iowans planning to vote on Jan. 3 support Obama, compared to 29 percent for Clinton and 20 percent for Edwards.

Giuliani, who was New York mayor during the Sept. 11 attacks, issued a Web ad wishing for peace with strength, secure borders against illegal immigration and lower taxes.

"And I really hope that all of the presidential candidates can just get along," he says. A red-suited Santa Claus chimes in: "Ho, ho, ho. I was with you right up until that last one."

Obama's ad featured him, wife Michelle and their two children in front of a Christmas tree with a message that highlights "the things that unite us as a people."

Clinton, in her ad, is surrounded by festively wrapped gifts labeled with her wishes, such as "bring troops home."

(To read more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at

blogs.reuters.com/trail08/

)