"He was on board with that amnesty policy, which many Americans opposed," Bachmann said Saturday, according to Fox News. "This isn't for people who've been here for 25 years. This is a path of amnesty for people who are here in the United States. ... If he's only talking about people who have been here for 25 years, that would be completely different than the letter that he published in The Wall Street Journal."

Gingrich has repeatedly rejected Bachmann's characterization of his position, telling Fox News last Thursday that suggestions his proposal would provide blanket amnesty were "explicitly false."

Gingrich returned to the criticism Wednesday.

"What I will say," Gingrich said, "is that the voters will be pretty good over time in distinguishing between people who know facts and people who don't know facts … people who are focused on positive, large solutions, not people who are trying to pick fights."