A month ago, Rasmussen was one of the first pollsters to pick up on Newt Gingrich’s momentum, showing him up 13 points over Mitt Romney in Iowa, 32/19.  If Rasmussen has its finger on the pulse of Iowa voters, that momentum didn’t last long.  Today’s Rasmussen poll shows Gingrich losing twelve points since November 15th and falling behind Romney for second place, at 23/20:

Take a look at the stability in Romney’s numbers — and the instability in almost everyone else’s.  Scott Rasmussen points this out in the video.  The only other candidate who’s had any stability at anything above the signal-noise level is … Ron Paul, who’s back to about where he was in August before Rick Perry and Herman Cain had their bubble moments.

The internals show some interesting points.  Gingrich captures 27% of “very conservative” respondents, but Romney gets 17%, good for second place.  Romney wins the “somewhat conservative” demo by ten points at 29/19 over Gingrich, and not surprisingly, the “other” category at 22%.  Paul comes in second rather than third in this last demo at 19%.  Rick Perry ties for third place at 14% among very conservative respondents, falls well back to fourth place at 10% in the intermediate group, and drops to 6% among “others.”  If Perry wants to get enough of a bounce to compete in two weeks, he needs to either start grabbing a lot more of Gingrich’s “very conservative” support or look for ways to attract the “somewhats.”

Here’s an interesting note from the internals.  For all of the class-warfare bombs being tossed by both Gingrich and Romney, Romney beats Gingrich in every income demographic in Iowa except the $75-100K group.  Paul, though, beats both in the under-$20K and $60-75K demos.

Romney also leads among people who have made up their minds, 29% to 22% for both Gingrich and Paul, but he also slightly leads those who could change their mind, too — 22/21 over Gingrich, with Paul third at 17%.  Perry only gets 7% while he has 14% among those who could change their minds, which means that he is just beginning to convince people to rethink his candidacy.  Time is definitely running out for Perry, in other words.  Among those certain to show up at the caucuses, Romney’s lead expands to 25/21 with Paul dropping to 17%, and Romney even leads among those not certain to show up, 20/18/18.

It looks like Gingrich has a momentum problem in Iowa.  If he can’t close the deal here, can he remain viable in South Carolina and Florida?  It’s possible, but given his large polling advantage just days earlier, I’d be a little skeptical.  This looks like a re-evaluation based on the heightened scrutiny of Gingrich’s record, and it seems that voters may be having second thoughts.