Now Gingrich is going on the offensive, using Twitter to tweak Romney.
"Here's a trip down memory lane," Gingrich tweeted with a link to a 2007 "Meet the Press" video. So what's your position on citizenship for illegals again?
You can judge for yourself whether Romney used to have a different position in 2007 than in 2011. Back then, legal status - even citizenship was okay, but now it would be amnesty.
"My own view is, consistent with what you saw in the Lowell Sun, that those people who have come here illegally, and are in this country, the 12 million or so that are here illegally, should be able to sign up for permanent residency or citizenship," Romney said.
Here's a thought - Romney has always seemed vulnerable on the "flip-flop" issue, but it hasn't really stuck.
Will part of Gingrich's ascension to the top of the GOP field mean sharper attacks on Romney highlighting those policy changes over the years?
There is a 200 page playbook out there of opposition research on Romney that was done by the campaign of Sen. John McCain (R-AZ) four years ago.
Something to consider.