On Nov. 19, 2015, then-presidential candidate Donald Trump made a public proposal that would come to be a defining moment in his campaign.

Prompted by a question from NBC reporter Vaughn Hillyard as to whether a national registry of Muslims was something Trump would endorse, the GOP candidate declared that he would "absolutely" and "certainly" create a database of Muslim citizens living in America.

Earlier that day, Trump had taken the recent terrorist attacks in Paris as an opportunity to claim that "security is going to rule" and that "certain things will be done that we never thought would happen in this country in terms of information and learning about the enemy."

The answer, along with Trump's vagueness about how such a registry would work, other than depending on "management," set off a frenzy among reporters. Trump immediately walked it back, demanding to know where reporters heard that answer, while also claiming he hadn't actually answered the question and that he never mentioned or endorsed a Muslim registry.

The response from much of the public was harsh derision. A former Marine who happens to be a Muslim, Tayyib Rashid, started a trend in November 2015 of Muslim military and government personnel posting their IDs with the hashtag #MuslimID.

Despite the backlash, on Dec. 7, 2015, Trump went even further. He advocated for an official policy of barring all non-American Muslims from entering the United States - everyone from potential refugees to tourists. In a press release, Trump said:

"Donald J. Trump is calling for a total and complete shutdown of Muslims entering the United States until our country's representatives can figure out what is going on."

The proposal outraged the Obama administration officials and left-leaning pundits, but after a flurry of concern, it disappeared from Trump's campaign plank. By summer 2016, the "total and complete shutdown" had morphed into a ban on immigration by Muslims "from any nation that has been compromised by terrorism."

He wasn't specific about what countries this would include. Trump, also, didn't see this as a walking back, but as an expansion - despite reducing the total ban to a partial ban. As he told NBC's Chuck Todd in July:

"I actually don't think it's a rollback. In fact, you could say it's an expansion. I'm looking now at territory. People were so upset when I used the word Muslim. Oh, you can't use the word Muslim. Remember this. And I'm OK with that, because I'm talking territory instead of Muslim."

Trump's position on the Muslim ban remained unclear even after the election. The section of his website promising "a total and complete shutdown of Muslims entering the United States" had still been up, even though the candidate had seemingly moved off the position - but then was briefly removed, before being put back up.

It was only the possibility of Kansas Secretary of State Kris Kobach being nominated as Trump's attorney general that brought the "Muslim registry" into more focus. Kobach, who lost out on the post to Sen. Jeff Sessions, R-Ala., had written much of the 2002 National Security Entry-Exit Registration System (NSEERS), a registry that the Bush administration enacted to crate a watch-list for what it deemed to be potential terrorists.

NSEERS entailed the fingerprinting and interrogating of people from "high-risk" countries where extremist groups are active, along with the tracking of some males ages 16 and older. Numerous complaints about the legality and effectiveness of the system prompted the government to shut it down.

But with Kobach on the Trump transition team, it seems likely some form of a Muslim registry resembling NSEERS will be enacted.

The constitutionality of the original Muslim ban was never tested - but with NSEERS, or a derivative of it, the Trump administration will have the tools in place to register, track, and deport Muslims - no matter what country they're from.