In what would be a stunning reversal on an issue central to his candidacy, Donald Trump floated a possible process to allow undocumented immigrants to remain in America in a town hall that aired Wednesday.

"No citizenship,” Trump told Fox News' Sean Hannity in an interview taped Tuesday afternoon in Austin, Texas. "Let me go a step further — they'll pay back-taxes, they have to pay taxes, there's no amnesty, as such, there's no amnesty, but we work with them."

Trump said he was moved by concerns from fans who opposed his previous calls for a "deportation force" to remove all of the estimated 11 million undocumented immigrants in the country.

"When I look at the rooms and I have this all over, now everybody agrees we get the bad ones out," Trump said. "But when I go through and I meet thousands and thousands of people on this subject...they've said, Mr. Trump, I love you, but to take a person that has been here for 15 or 20 years and throw them and the family out, it's so tough, Mr. Trump."

Republican presidential candidate Donald Trump welcomes Nigel Farage, ex-leader of the British UKIP party, to speak at a campaign rally in Jackson, Miss., Wednesday, Aug. 24, 2016. Gerald Herbert / AP

While Trump's comments on legalization were inconsistent in the years leading up to his presidential run, he maintained during the primaries that all undocumented immigrants must be removed throughout his campaign.

At one point he proposed expelling all 11 million undocumented immigrants within two years — a goal that experts say would require a brutal and expansive deportation regime to carry out.

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But Trump has a tendency to flip flop on policies, sometimes issuing detailed white papers only to contradict them in public or abandon them entirely later on. He recently disavowed a tax plan he released earlier in the race and is currently hedging on whether his plan to ban all Muslim travel, a signature campaign proposal that is still on his website, remains his current position.

He sounded unsure of his own immigration position on Tuesday, at one point turning to the audience to survey them on the issue.

"Look, this is like a poll, there's thousands of people in this room," Trump said. "Who wants those people thrown out?"

He later asked "Who does not want them thrown out?" and concluded "there weren't that many for the number two, but the few people that stood up, I get that."

But while Trump fell far short of making any concrete pronouncement, his open discomfort with his prior call to remove all undocumented immigrants and not just "bad ones" who committed serious crimes was a jarring shift for a candidate who had outflanked 16 Republican rivals on the issue during the primaries.

The "back taxes" line in particular leapt out to observers. A common plank of various immigration reform proposals to provide a path to legal status for undocumented immigrants is a requirement that they pay back taxes in the process.

The bipartisan "Gang of Eight" bill that passed the Senate in 2013 before dying in the House included such a provision in addition to requirements that qualifying immigrants pass a criminal background check, learn English, and live in the country on a trial basis for 10 years before becoming a permanent resident and eventual citizen.

Trump's "no citizenship" pledge, while counter to the "Gang of Eight" bill, nonetheless echoed other immigration proposals from other Republicans that Trump had explicitly denounced as "amnesty" for entertaining legal status for some undocumented immigrants.

Former Florida Governor Jeb Bush, for example, co-authored a book outlining an immigration reform plan that would grant earned legal status to undocumented immigrants but permanently bar them from citizenship. Texas Senator Ted Cruz also floated a possible compromise involving legal status short of citizenship during the 2013 immigration debate. While Cruz later renounced the idea and denied having seriously considered it in the first place, Trump attacked him over the proposal without hesitation.

“Ted was in favor of amnesty,” Trump told CNN shortly before the Iowa caucus earlier this year.

Any move by Trump towards legalization would risk alienating his more hardline supporters. At outlets like Breitbart, whose president Steve Bannon recently took over as CEO of Trump's campaign, Republicans who support a path to legal status are frequently attacked as "amnesty" supporters who sold out the conservative base. Alabama Senator Jeff Sessions, one of Trump's closest advisers, is also a leading opponent of such efforts.

"There's nothing Trump can do that won't be forgiven," Trump supporter Ann Coulter wrote in her new book "In Trump We Trust: E Pluribus Awesome." "Except change his immigration policies."

Trump also would risk opening up his other key promises to supporters to renewed scrutiny. Most notably, he could unnerve conservatives who are voting for his candidacy with reservations because he has pledged to appoint judges they favor.

But there's upside as well. Trump's down in the polls by a significant margin to Hillary Clinton in part due to his abysmal numbers with Hispanic voters as well as suburban white voters who are less comfortable with hardline calls for mass deportation than Trump's blue collar rural base.

Whether those voters would trust entreaties from a candidate with a history of inflammatory positions and rhetoric who seems poised to potentially abandon his most loyal backers on a whim in the heat of a general election is an open question.