Donald Trump’s idea for a hold on Muslim immigration to the United States has stoked controversy and confusion since he first proposed it in the wake of a deadly terrorist attack at a California holiday party in December 2015.

Initially, Trump offered up an ironclad ban that would affect even Muslim-Americans traveling abroad. In the ensuing months he’s pitched modified versions of that proposal, and as of this week, Trump says the proposed ban would affect only those coming from “terrorist countries” with a sustained record of attacks.

It seems as if every time the press scrambles to make sense of the latest iteration of Trump’s Muslim ban, the candidate or one of his staffers shifts the terms again. Even members of his own campaign team seem unclear on where exactly their candidate stands on the ban, which has been condemned by everyone from House Speaker Paul Ryan (R-WI) to President Barack Obama.

TPM tracked the shifts in Trump’s proposal over the course of the 2016 campaign, from special exemptions for the real estate mogul’s friends to a broadening to immigrants from parts of the world with a “history of terrorism.”

A ‘total and complete shutdown’

On December 2, a married couple who had self-radicalized online went on a shooting spree at an office holiday party in San Bernardino, California, killing 14 people and gravely wounding 22 more. Five days later, Trump released a statement calling for a “total and complete shutdown” of Muslim immigration.

“Until we are able to determine and understand this problem and the dangerous threat it poses, our country cannot be the victims of horrendous attacks by people that believe only in Jihad, and have no sense of reason or respect for human life,” Trump said in a campaign press release.

Questions quickly arose about how such a ban on the world’s 1.6 billion followers of Islam could be enforced and to whom it would apply, given that the San Bernardino shooting was carried out by Syed Farook, a U.S. citizen of Pakistani descent, and his wife Tashfeen Malik, a Pakistani-born lawful permanent resident.

Corey Lewandowski, Trump’s campaign manager until last week, said at the time that the proposal would apply to Muslims visiting the U.S. as tourists as well as those pursuing immigration visas. Even American Muslims traveling abroad would be banned from reentering the U.S.

As spokeswoman Hope Hicks said at the time, “Mr. Trump says, ‘everyone.’”

Trump’s friends, vets, U.S. citizens would be exempt

In an interview with Fox News’ Greta van Susteren the night that he proposed the ban, Trump began the long process of moderating the “complete shutdown” stance. He allowed that Muslims already living in the U.S., including friends of his and Muslim-American members of the military, would not be affected by the ban.

“They’ll come home. And we have to be vigilant,” Trump said of military members returning from overseas duties.

Trump defended the ban and repeated the vague timeline for its enforcement that he laid out in his original statement, insisting, “We have to figure out what’s going on.”

Muslim world leaders and athletes would be exempt

In a round of morning show phone-in interviews the next morning, Trump laid out some further exceptions to the proposal and offered a few details about how it might be enforced.

On MSNBC’s “Morning Joe,” Trump said there were “certainly going to be exceptions made” for Muslim athletes visiting the U.S. for sporting events and for the leaders of Middle Eastern countries.

He told MSNBC’s Willie Geist that one way the ban could be enforced would be to have customs officers ask airline passengers if they’re Muslims either before they depart for the U.S. or after they arrive here. If they answer “yes,” they would be refused entry.

“It could happen at the site, it could happen here, it could happen in many different forms,” Trump said.

Trump was similarly ambiguous on how long the ban would remain in place. He told Geist he would know when to lift it by “a feel or a touch.”

Trump renews call for ban after Brussels attacks

Coordinated terrorist attacks at a subway station and international airport in Brussels that killed at least 34 people and injured over 300 reignited Trump’s calls for a ban in March. On the day the nail bombings went off, Trump said the U.S. had “no choice” but to bar Muslim immigration.

“You’re going to make certain exceptions, and exceptions on heads of state and some of these people and I’m not saying we don’t do that,” Trump told CNN’s Wolf Blitzer. “But we have a real problem and people don’t have any idea what’s going on. We have a government that’s impotent, a government that doesn’t get it.”

Trump stands by ban after becoming presumptive nominee

Trump clinched the number of delegates needed to secure the GOP nomination with his victory in the Indiana primary on May 3, and his last opponent standing, Ohio Gov. John Kasich, dropped out of the race on May 4. With his new title as presumptive nominee cemented, Trump went on NBC’s “Nightly News” to defend his immigration proposals.

Asked by host Lester Holt if he stood by his plan to bar Muslim immigrants, Trump said, “I do. We have to be vigilant. We have to be strong.”

London’s new Muslim mayor would be exempted

After Sadiq Khan was elected as London mayor, Trump said that his exemptions for Muslim heads of state would also include lower-tier Muslim officials.

“There will always be exceptions,” Trump told The New York Times, calling Khan’s election a “very good thing.”

Trump says the proposed ban was ‘just a suggestion’

In perhaps the most dramatic walk-back of his initial plan for a “complete and total shutdown” of Muslim immigration, Trump made the breezy claim in a Fox News interview that the entire proposal was just a “suggestion.” He noted that the ban was only “temporary,” after all.

“It’s a temporary ban. It hasn’t been called for yet. Nobody’s done it. This is just a suggestion until we find out what’s going on,” Trump told Fox News’ Brian Kilmeade.

Top advisor says Trump will soften his stance on the ban

Senior adviser Paul Manafort assured voters that Trump’s proposal was not set in stone and would be softened as the campaign moved into the general election phase.

“He’s already started moderating on that,” Manafort told the Huffington Post. “He operates by starting the conversation at the outer edges and then brings it back towards the middle. Within his comfort zone, he’ll soften it some more.”

“He’ll still end up outside of the norm, but in line with what the American people are thinking,” he added.

Trump champions ban again after Orlando attack

In the early morning of June 13, Omar Mateeen went on a shooting spree at the Pulse gay club in Orlando, Florida, killing 49 and injuring 53. Within hours, Trump had applauded his own foresight in anticipating more terrorist attacks on U.S. soil. For Trump, the mass shooting proved why a ban was necessary, even though Mateen was a U.S. citizen and wouldn’t have been affected by Trump’s ban according to his own specifications.

“What happened in Orlando is just the beginning,” Trump said in a tweet. “Our leadership is weak and ineffective. I called it and asked for the ban. Must be tough.”

Ban applies to parts of world with ‘history of terrorism’

In a national security speech the day after the Orlando attack, Trump appeared to suggest broadening the ban significantly to outlaw immigrants from any country with a documented history of attacks against the U.S. and its allies.

“When I’m elected, I will suspend immigration from areas of the world where there is a proven history of terrorism against the United States, Europe or our allies until we fully understand how to end these threats,” Trump said, making no specific reference to religion.

The presumptive GOP nominee also again alleged that Omar Mateen, a second-generation immigrant, was only able to carry out his mass shooting because of the nation’s “immigration system.”

“The bottom line is that the only reason the killer was in America in the first place was because we allowed his family to come here.”

Christie argues the proposal isn’t actually a ‘Muslim ban’

New Jersey Gov. Chris Christie (R) told reporters last week that he has tried to teach Trump to better spin issues like the ban in his role as an adviser to his onetime rival. According to Christie, Trump’s strident tone gives the press false impressions of his policies.

“You all continue to call it a Muslim ban. That’s not what it is and never has been,” Christie told reporters, according to the Bergen Record. “So I’ve urged him to continue to speak in detail about this, so that it prevents the media from short-handing something and making him look like something that he’s not.”

Trump only wants to ban Muslims from ‘terrorist countries’

While touring his new golf course with reporters Saturday in Scotland, Trump attempted to narrow the scope of the ban slightly.

“I want terrorists out. I want people that have bad thoughts out. I would limit specific terrorist countries and we know who those terrorist countries are,” he told the Washington Post.

Spokeswoman Hope Hicks told the Post in a follow-up email that this position was made clear in Trump’s national security speech. Trump didn’t mention Muslims in that speech, however, and his proposal to ban “certain people” from countries with “tremendous terrorism” was widely interpreted as Trump broadening the ban to cover even more people.

Spokeswoman says Trump isn’t actually changing his stance

Trump spokeswoman Katrina Pierson insisted in a Monday interview that proposing to ban immigrants from countries with a history of frequent terrorist attacks was not the same thing as proposing to ban immigrants specifically because they are Muslim. Pierson said that shift represented a mere “refining” of the proposed ban.

“We’ve said this a number of times throughout the few months,” she said on CNN. “Mr. Trump is going to be refining his policy — putting out more specific details, which everyone’s been asking for, but there has been no change. He still does not want to allow individuals to come into this country who cannot be vetted.”

Surrogate argues the ban was never about religion

Top Trump surrogate Carl Paladino insisted that the ban had nothing to do with faith, and that consistent positions were a lot to ask during an election year.

“I don’t think it was ever a ban directed at religion,” he said, adding that “expecting a clear definition is a little bit much in the middle of a presidential campaign.”