TRENTON -- Donald Trump's apparent pivot away from his calls for mass deportations of millions of undocumented immigrants is partially the result of prodding by New Jersey Gov. Chris Christie, according to former New York Mayor Rudy Giuliani.

And, Giuliani says, even more Christie-inspired changes to Trump's immigration stance will be forthcoming, like his call for tracking immigrant visas like Fedex packages, and using the E-Verify system to reduce illegal labor.

In an interview with NJ Advance Media on Thursday, Giuliani, a top adviser to the Republican presidential nominee, said Trump's recent reversal on immigration policy came after his inner circle for several weeks suggested a more nuanced, practical, and humane approach in dealing with the nation's 11 million undocumented immigrants.

Asked if Christie was responsible for Trump's softening approach to immigration, the former mayor responded: "The answer to that question is yes."

Christie, Giuliani said, "is not the only one" counseling a more moderate stance on those who immigrated illegally, "but he is of great value to him."

The Trump campaign declined to comment on Christie's involvement. The governor is an adviser to Trump and heads his transition effort.

A spokesman for Christie declined to comment.

Last summer, Trump vowed to employ a "deportation force" to expel all undocumented immigrants from the U.S.

"Politicians aren't going to find them because they have no clue," Trump told CNN's Dana Bash in July 2015. "We will find them, we will get them out," Trump said. "It's feasible if you know how to manage. Politicians don't know how to manage."

But on Wednesday, Trump appeared at a town hall meeting with Fox News' Sean Hannity and said he wasn't sure if he wanted carry through on his prior promises to tear out the nation's entire unauthorized immigrant population root and branch.

"Can we go through a process, or do you think they have to get out? Tell me. I mean, I don't know. You tell me," Trump said to the crowd, which greeted his question with a mix of boos and cheers.

The reappraisal stunned many Trump supporters, who noted that their candidate was adopting the proposals of former rivals Jeb Bush and Marco Rubio. Trump had previously ridiculed their calls to establish permanent residency for undocumented immigrants and an agricultural worker program.

Bush, the former governor of Florida, himself sounded off on the matter on Thursday in a radio interview with ABC News.

"Shifting my views because, because it's political to do it? That's what politicians do in this country, that's what Trump is trying to do right now," Bush said. "I find it abhorrent."

However, Trump's reversal is similar to proposals put forward by Christie just before his own presidential run.

"There are not enough law enforcement officers in all the country if all they were doing is rounding up and deporting people," Christie said during an town hall in Exeter, N.H., in April 2015, just two months before launching his presidential bid.

"I will tell you that most folks that I've met in my state who have come here to this country illegally, have come here because they want to work," Christie said at a town hall in Londonderry, N.H., that same month. "Because they want to support themselves, they want to support their families."

On Thursday, Giuliani said that Christie's immigration advice to Trump has become "an important part of the discussion and his views are taken very seriously."

Trump is polling poorly with Latinos. A recent NBC News poll found 22 percent of Hispanic voters support Trump, compared with the 73 percent who back Clinton.

In addition, Giuliani said two significant planks from Christie's own immigration plan will be announced as part of Trump's border security approach in the weeks ahead.

"He's going to talk about biometrics and E-Verify," Giuliani said, referring to Christie's previous calls to track immigrant visas like overnight packages, and for all employers to make mandatory use of the U.S. Department of Homeland Security's E-Verify system, which allows businesses to determine the eligibility of their employees to work in the U.S.

In August 2015, Christie said he was "going to ask Fred Smith, the founder of Federal Express, to come work for the government for three months at Immigration and Custom Enforcement" to create "a system that tracks you from the moment you come in."

In July 2015, Christie repeatedly called for expanding use of the E-Verify system, calling it the "most important" tool the government could use to curtail illegal immigration.

"If every employer uses E-Verify and if they violate the law, there are fines that are so significant that the profit they make off hiring lower-wage workers and discriminating against American workers won't be worth their while," Christie told Fox News.

On Thursday, Giuliani said he suspected Trump would embrace a guest worker program for those immigrants who entered the country illegally as migrant farm or livestock workers, but only after securing the border.

"There's nothing that prevents having a program in which the people who are willing to do jobs that aren't being filed by Americans, if it's managed correctly and doesn't result in illegal immigration," Giuliani said.

He added that whatever static Trump's reconsideration of his deportation plan was generating among supporters, the mogul still had plenty of wiggle room.

"Either position that he takes, he can get elected," Giuliani said. "I've been to many rallies with him. Nobody at the rallies is terribly concerned about the number of illegals who are not committing crimes. Their big concern is the wall. I would consider that the core promise that he made."

NJ Advance Media staff writer Brent Johnson contributed to this report.

Claude Brodesser-Akner may be reached at cbrodesser@njadvancemedia.com. Follow him on Twitter @ClaudeBrodesser. Find NJ.com Politics on Facebook.