Meanwhile, former Massachusetts Gov. Mitt Romney has seen his support drop in both states.
In Iowa, which holds its caucuses on Jan. 3, Gingrich gets the support of 26 percent of likely caucus-goers (including those leaning towards a candidate) -- a 21-point jump since October.
Read the NBC News-Marist poll Iowa Annotated Questionnaire
He’s followed by Romney at 18 percent (an eight-point decline), Texas Rep. Ron Paul at 17 percent (a five-point increase), Herman Cain at 9 percent (an 11-point drop) and Texas Gov. Rick Perry at 9 percent (a two-point dip). No other Republican presidential candidate gets more than 5 percent support among likely caucus-goers.
With Cain’s decision to suspend his campaign -- which he announced on Saturday -- a reallocation of his supporters’ second-choice picks puts Gingrich ahead of the Iowa horse race with 28 percent; Paul and Romney are tied at 19 percent; and Perry lands at 10 percent. (The NBC-Marist polls were conducted before Cain suspended his campaign.)
Among all Republican respondents in Iowa, the breakdown is Gingrich with 25 percent, Romney at 18 percent and Paul at 16 percent