Huckabee has a commanding lead in Iowa, according to a new poll.

WASHINGTON (CNN) - A new poll of Iowa voters conducted this week seems to show Mike Huckabee surging past the rest of the Republican field, beating his closest rival, former Massachusetts governor Mitt Romney, by 22 points among Republicans, 39 to 17 percent.

In the latest Newsweek poll, released Friday, former Tennessee senator Fred Thompson slides to 10 percent, down from 16 in the last survey. No other candidate rates higher than single digit support.

Polling in Iowa is notoriously difficult because of the unpredictable nature of caucus attendance. And most recent surveys have pictured a much tighter race.

Still, the poll, conducted December 5 and 6, comes after weeks of momentum for the former Arkansas governor’s campaign, fueled by increased support from social conservatives, who form a major bloc of Iowa’s GOP caucus-goers.

Among likely Republican caucus-goers, the margin is just as wide. Fifty-seven percent name Huckabee as their first or second choice, and 39 percent give Romney as their first or second choice. Again, Thompson is third, with just 20 percent.

The Romney campaign said that the new survey showed a crowded field narrowing to a two-man race. “Iowa is in a competitive state right now as far as public polling is concerned,” said Kevin Madden, Romney’s spokesman, in an e-mail to CNN.

He also cast Mitt Romney as the campaign’s new underdog. "Mike Huckabee is leading and with that lead comes much higher expectations and a greater degree of scrutiny of his weak position on immigration and his penchant for big spending and higher taxes," he said.

A senior Romney adviser tells CNN's John King on the condition of anonymity that the poll result is "not a surprise" and there is "not a lot of time to turn them around," while another adviser says the 22 point lead for Huckabee sounds "a little extreme but he (Huckabee) is the moving part out there."

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