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Rep. Michele Bachmann on Saturday stood by her claim that Newt Gingrich supports "amnesty" for illegal immigrants, digging up a letter the former House speaker signed nearly eight years ago to combat claims that she was misrepresenting his plan.

Gingrich, after saying at a Republican presidential primary debate that the U.S. should afford some illegal immigrants a pathway to legal status, has clarified that he only wants to open that door for some illegal immigrants who have been in the country 25 years or more.

Bachmann, in an interview with Fox News, cited a 2004 letter Gingrich co-authored expressing support for then-President George W. Bush's immigration plan. The letter applauded Bush's proposed guest-worker program, while endorsing "paths to permanent residence to enable more workers to stay, assimilate, and become part of America." The letter, which was published in The Wall Street Journal, praised Bush for recognizing that "those already working here outside the law are unlikely to leave."

While the letter did not call for legalizing every illegal immigrant, Bachmann said it didn't draw a distinction between recent illegal immigrants and those who have been in the U.S. for decades either.

"He was on board with that amnesty policy which many Americans opposed," Bachmann said Saturday. "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."

In a separate written statement, Bachmann said the letter indicates he is "the most liberal candidate" on immigration.

But Gingrich, as a presidential candidate, is not necessarily reviving the plan from the Bush administration. And Gingrich and his campaign have been explicit in explaining that his proposal would not involve blanket amnesty for 11 million illegal immigrants.

"This is explicitly false," Gingrich told Fox News on Thursday.

Gingrich spokesman R.C. Hammond on Saturday rejected Bachmann's interpretation of the 2004 letter.

"Two things are going on: either the congresswoman is intentionally lying to people or she does not understand immigration reform," he said in an email to Fox News. "Either way it is sad to see from a presidential candidate."

Gingrich was also just one of 15 people who signed the letter Bachmann referenced.

Gingrich said Thursday he's in favor of "deporting all recent unattached illegals." He said he then wants a "local citizen panel" to consider whether law-abiding, taxpaying illegal immigrants who have been here 25 years or more "and have family and community" should be allowed to stay.

Gingrich, citing a plan from the Vernon K. Krieble Foundation, said some of those individuals could get a "red card" allowing them to be legal, but not giving them a path to citizenship or the right the vote.

Rep. Michael Burgess, R-Texas, a Gingrich supporter, told Fox News on Saturday that Gingrich is committed to border security, but said lawmakers are not always "intellectually completely honest" about what to do with the illegal immigrants who remain in the country once the border is secured. "We all know there are going to be compelling stories that have to be dealt with," Burgess said.

Gingrich said at the debate Tuesday he is willing to take the heat that may come with these beliefs to stand up for the rights of families.

"Let's be humane in enforcing the law without giving them citizenship but by finding a way to create legality so that they are not separated from their families," he said.

Gingrich's opponents in the 2012 race quickly seized on his proposal to hammer him as soft on illegal immigration.

Bachmann fired off a statement during the debate accusing Gingrich of supporting amnesty. She repeated the claim during an interview on Fox News the following day.

In response, Gingrich's campaign said Bachmann was "lying" about the former speaker's immigration plan.

"We want it made clear Newt is not for amnesty," Hammond said. "He is the only candidate with a solution for what to do with illegal immigrants who are already here."

Gingrich's illegal immigration stance has created a challenge for him as he rises to the top of several national polls, edging out even former Massachusetts Gov. Mitt Romney -- who has been at or near the top of the field for much of the campaign.

Bachmann, meanwhile, has watched her level of support steadily decline since entering the race.

A Quinnipiac University poll released Tuesday showed Gingrich leading the field with 26 percent, Romney in second with 22 percent and Bachmann several places back with 4 percent.

With his rise, Gingrich has started to attract more attention on the trail. He drew his largest crowd to date Friday at a town hall meeting in Naples, Fla. -- about 750 people attended.

But Bachmann described the candidate's immigration stance as a "magnet to bring more people into the United States."

Plus she questioned whether Gingrich's proposed "citizen" panels would have "quasi-judicial" powers, and where they would derive that authority from.

If they applied the law of the land, Bachmann said, "then people would need to be deported, because that's what the law of the land is."