Romney’s healthcare plan has been the focus of attacks by his rivals, who say it was the model used by the Obama administration in implementing the Affordable Care Act. The individual mandate was the centerpiece and most controversial aspect of the act, which has widely been blasted by Republicans as government overreach.

But in a memo discovered Monday on an old Gingrich website by Andrew Kaczynski at Buzzfeed, Gingrich said then-Gov. Romney should be “commended” for passing a universal healthcare package.

“We also believe strongly that personal responsibility is vital to creating a 21st Century Intelligent Health System,” Gingrich wrote. “Individuals who can afford to purchase health insurance and simply choose not to place an unnecessary burden on a system that is on the verge of collapse; these free-riders undermine the entire health system by placing the onus of responsibility on taxpayers.”

That differs sharply from the former House Speaker’s words in a 2010 interview with Bill O’Reilly on Fox News.

"It's the forerunner of ObamaCare," Gingrich said. "It is a general model in a general direction and it's the general direction that's wrong. And that's why I'm suggesting you need to be thinking about fundamental change, not just marginal reforms."

Gingrich has admitted that his long history in Washington has necessitated that at times he change positions on issues due to changing circumstances. However, many conservatives see Romney’s healthcare law as the biggest strike against him.

All of the Republican presidential candidates have vowed to repeal the Affordable Care Act if elected president.