Gallup tends to lag other polling like Rasmussen, in that it seems to take longer to filter results to the Gallup poll. Nevertheless, a mid-December poll shows Gingrich within striking distance of Obama, Election 2012 Trial Heat: Obama vs. Gingrich. Granted, there's a lag, but that puts Gingrich in the same striking distance as Romney.
Meanwhile Romney has pulled back ahead of Gingrich nationally.
Take it all with a grain of salt.