House Speaker Newt Gingrich and his wife Callista buy a pork chop lunch as they campaign at the Iowa State Fair in Des Moines, Iowa. (Charles Dharapak/AP)

Having just taken his place at the front of the Republican presidential pack, Newt Gingrich now faces a potential backlash from conservative activists here in Iowa over an immigration proposal that he called “humane” but that his opponents quickly decried as providing “amnesty.”

The former House speaker appears to have alienated some of the conservatives who had warmed to his candidacy by saying Tuesday in a candidates debate that he would allow millions of illegal immigrants who have settled in the United States to become legal residents.

Republican leaders across Iowa — including grass-roots activists, county party chairmen and a congressman — said on Wednesday that Gingrich could see an erosion in his support here, just as Texas Gov. Rick Perry did when his moderate immigration positions became clear.

Tim Albrecht, a top aide to Gov. Terry Branstad (R), said Gingrich’s comments will prove “toxic.” He predicted that other candidates would “tear him up on this issue.”

“The climate changed for Newt Gingrich [Tuesday] night,” added Albrecht, who worked for Mitt Romney’s 2008 campaign and is neutral now because he’s working for Branstad.

In Iowa in particular, immigration politics inspires passion among conservatives. “They believe, as I do, that any form of amnesty is not supported,” said Ann Trimble-Ray, chairman of the Sac County Republican Party. “If you have broken the law, then you need to pay the consequences of having done so. If that means deportation, so be it.”

She added: “We still respect Speaker Gingrich for all he is, which is a very intelligent man who understands how the process works in the United States government and is bringing a valuable perspective in many, many ways in this race, but I think this probably is a deal breaker for some folks.”

Brian Rosener, chairman of the Woodbury County Republican Party, said: “The only conversation that needs to happen on the immigration issue is how to secure the border. Any other discussion is, at some point, dangerous and irresponsible.”

Gingrich’s campaign moved to quell any possible uprising among supporters here. Dan Seufferlein, who is coordinating Gingrich’s efforts in eastern Iowa, said he called a dozen conservative activists on Tuesday night and Wednesday morning to explain the candidate’s position. He said that only one activist mentioned Gingrich’s debate answer.

“I could be wrong, but my judgment is that this is manufactured outrage by some of the other campaigns that are looking to stall his numbers and increase theirs,” Seufferlein said.

In the debate, Gingrich said: “If you’ve come here recently, you have no ties to this country, you ought to go home. Period. If you’ve been here 25 years and you got three kids and two grandkids, you’ve been paying taxes and obeying the law, you belong to a local church, I don’t think we’re going to separate you from your family, uproot you forcefully and kick you out.”

During a visit here Wednesday, Mitt Romney seized on Gingrich’s remarks and accused his rival of offering “a new doorway to amnesty.”

“I just think we make a mistake as a Republican Party to try to describe which people who’ve come here illegally should be given amnesty to be able to jump ahead of the line of the people who have been waiting in line,” he said at a news conference after a town hall meeting at a Des Moines insurance company.

“My view is that those people who have waited in line patiently to come to this country legally should be ahead in line,” Romney continued, “and those who’ve come here illegally should not be given a special deal or a special accelerated right to become a permanent resident or citizen.”

Gingrich's campaign accused Romney and other opponents, including Rep. Michele Bachmann (Minn.), of distorting Gingrich’s position. “Governor Romney can certainly shovel it, but that doesn’t mean Iowa will believe it,” Gingrich spokesman R.C. Hammond said.

Gingrich used Twitter on Wednesday to take a swipe at Romney, sending a tweet to the former Massachusetts governor: “Here’s a trip down memory lane.” Gingrich’s tweet included a link to a 2007 “Meet the Press” interview in which Romney seemed to be open to permanent residency or citizenship for some illegal immigrants. But Gingrich edited out the latter half of Romney’s quote, in which he said immigrants should not have “a special pathway . . . merely by virtue of having come here illegally.”

Just two months ago, Perry’s standing fell in Iowa after he called “heartless” those who opposed a Texas law that grants in-state tuition to some undocumented immigrants. It was an open question whether Gingrich could suffer the same fate.

“Obviously the issue got ahead of Governor Perry before he could fully articulate what it was all about, and that’s the challenge for Newt Gingrich,” said Matt Whitaker, Perry’s Iowa campaign co-chairman. But, he added, “since we don’t have any perfect candidates, each one has got their unique issues that voters are going to have to reconcile with their own beliefs.”

Gingrich faces other hurdles, some of them organizational, including missing the filing deadline in Missouri to have his name on the ballot.

Steve Deace, a conservative talk-radio host here, said Gingrich will not face “Rick Perry-type fallout over his immigration remarks. He’s smarter than Rick Perry. Newt Gingrich didn’t look into an audience of tea party supporters and say, ‘If you don’t want to pay the college tuition of illegal aliens, you’re heartless.’ That’s just stupid.”

The question, Deace said, is whether voters will decide they can trust Gingrich.

“For Newt Gingrich, there’s two narratives: The good one is he’s ready to lead, he’s got chutzpah, he’s got brains and he’s your huckleberry,” Deace said. “The bad narrative is he does commercials with [former Democratic House speaker] Nancy Pelosi, he endorses [moderate GOP congressional candidate] Dede Scozzafava, he supported the TARP and then he opposed it, he’s been in Washington too long. There’s dueling narratives and it’s his actions that will determine which narrative Iowa voters see.”

Rep. Steve King, a tea-party-aligned Republican who represents northwest Iowa and whose endorsement has been coveted by many in the race, said Gingrich’s immigration views ran counter to “the rule of law — one of the essential pillars of American exceptionalism.”

“I think if Speaker Gingrich had that to do over again, he might couch his language differently, at a minimum,” King told Iowa Public Television.

Yet, this was Gingrich’s do-over. He made virtually the same comments about immigration at a September debate at the Ronald Reagan Presidential Library, where he said the United States must “find a way to deal with folks who are already here, some of whom, frankly, have been here 25 years, are married with kids, live in our local neighborhood, go to our church. It’s got to be done in a much more humane way.”

The difference is that, back then, Gingrich was a single-digit candidate. But on Tuesday night, he was a front-runner, and Iowans were paying attention.