The new Des Moines Register poll shows former House Speaker Newt Gingrich with a solid lead in Iowa, winning support from 25 percent of 401 likely Republican caucus-goers. That’s a huge shift — in October, Gingrich was at 7 percent.

Texas Rep. Ron Paul is in second place with 18 percent, rising from 12 percent in October. Former Massachusetts governor Mitt Romney has fallen from 22 percent to 16 percent.

Gingrich has been rising in various polls for the past two weeks, buoyed by solid debate performances and the scandal surrounding former Godfather’s Pizza CEO Herman Cain, who suspended his campaign on Saturday. Cain fell dramatically over the past month from 23 percent to just 8 percent.

Texas Gov. Rick Perry and former Pennsylvania Sen. Rick Santorum are tied at 6 percent, and former Utah Gov. Jon Huntsman is at 2 percent.

In previous Iowa polls Romney has always been close to the top, although various candidates challenged him for frontrunner status. His campaign, once keeping Iowa at arms’ length, has begun ramping up efforts there as it became clear that voters were not coalescing around any other candidate. But for now, at least, they are rallying around Gingrich, despite his rocky personal history.

Romney just went up with ads in Iowa, raising the stakes for him there. This poll suggests that winning the caucuses will be an uphill battle for him after all.

The Romney campaign did not expect a surge from Gingrich, who was left for dead a few months ago, and did not have a road map prepared to deal with him.

The poll is also notable for the rise of Paul, who has emerged as a major player in Iowa.

There’s room for change before the Jan. 3rd caucuses. Sixty percent of respondents said they were open to changing their picks. There’s room for growth for Gingrich there too — more respondents picked him as their second choice than any other candidate.