His border wall might be a fence. His political rival won’t rot behind bars. And the swamp he vowed to drain will likely fester for at least another four years.

The towering promises that helped propel Donald Trump to his stunning victory over Hillary Clinton three weeks ago are already shrinking to the rumored size of his hands. Unwavering on the campaign trail, the president-elect has begun to walk back his most extreme proposals, including his hardline pledges on immigration, health care, and torture.

The sudden —and sometimes startling — shifts mark yet another first in American politics, according to interviews with a half-dozen presidential historians and political scientists. Experts also say that Trump’s growing number of flip-flops undermine the weight traditionally ascribed to the words of a U.S. president and may invite a greater focus on those who will comprise his administration.

“It is all unprecedented — the scope of his promises and how quickly he reversed positions,” Sandy Maisel, the director of the Goldfarb Center for Public Affairs and Civic Engagement at Colby College, told Vocativ. “No one has made promises like Trump’s, which all rational observers knew were undo-able.”

Tweaked platforms and tempered rhetoric accompany every White House hopeful who wins their party’s grueling primary and pivots toward a general election, which tend to require a more moderate candidate. Trump is assuredly not the first president-elect to abandon a pledge that helped catapult him into office. Ronald Reagan galvanized Christian conservatives in 1980 when he vowed to pursue a constitutional amendment prohibiting abortion, a promise conveniently forgotten by him and his advisors after election day. In 2004, George W. Bush campaigned to impose a national ban on gay marriage, a proposal that similarly vanished once he eked out a win over John Kerry.

Scholars contend, however, that Trump’s string of apparent shifts and reversals land him in a league of his own. After vowing to “completely repeal” the Affordable Care Act, he has suggested that parts of the health care law, known as Obamacare, can stick around. His promise to sic a special prosecutor on Clinton, his Democratic rival, and deport 11 million undocumented immigrants from the United States now appear to be nothing more than the fever dreams of his angriest supporters. As is Trump’s stated desire to bring back waterboarding and “a hell of a lot worse,” which he now admits might not be such a great idea after all. Meanwhile, the president-elect remains mum on his onetime proposal to ban all Muslims entering the U.S.

“There was a degree of cynicism in his campaign about the things he was willing to say,” said David Greenberg, a presidential historian and professor at Rutgers University. “That really made it impossible that he wouldn’t be breaking or walking back a lot of his campaign promises.”

These pivots and U-turns might not matter much to many who cast their ballots for Trump, a businessman and reality television star with no prior political experience. Throughout the campaign, it became a common refrain among some of his supporters to note they understood the candidate’s most provocative pledges to be exaggerations. They, as the journalist Selena Zito observed, took Trump seriously, not literally.

Still, there already appears to be some limits to the amount of waffling the president-elect’s base will tolerate. Trump faced a searing backlash last week when he suggested that he would no longer pursue a criminal investigation against Hillary Clinton, a farfetched plan that nevertheless electrified his biggest supporters in the final weeks of the race. Furious fans erupted on social media. Conservative groups lashed out. Even Breitbart News, a pro-Trump propaganda mill during the campaign, declared “Broken Promise” in a blistering headline.

Of course, there is still the chance that Trump could reverse his most controversial proposals yet again. As a candidate in the Republican primary, he famously gave three different positions on abortion over the course of three hours. He appears to be equally flexible when it comes to the minimum wage.

“Trump’s words actually bear no relation to his actions,” David Hopkins, a professor of political science at Boston College, told Vocativ. “That’s something that we, as observers, will have to grapple with — a world in which rhetoric doesn’t mean any particular commitment or substantive action. That’s different from other presidents, needless to say.”

The president-elect’s fluctuating viewpoints is one of the reasons why experts are paying close attention to whom he appoints to his cabinet. Thus far, he seems well on his way to stacking his administration with the very Washington insiders and elites that he claimed to shun as a candidate, including billionaires, Wall Street bankers, and career politicians. Trump’s selection of Lieutenant General Michael Flynn as national security advisor, Alabama Senator Jeff Sessions as attorney general, and Georgia Congressman Tom Price as secretary of health and human services suggest that he remains focused on placing Islam, immigrants, and Obamacare in his crosshairs, despite any apparent wavering on his most extreme proposals.

“Trump, more than any other president of recent memory, will be very much influenced by these picks,” said Martin Cohen, a political scientist at James Madison University in Virginia. “He’s very malleable and doesn’t appear to have a lot of set feelings and thoughts. The first thing he hears and the last thing he hears might push him in one direction. That’s why this transition is extremely important.”

But for others, what precisely Trump will do come January remains anyone’s guess.

“We just have the least idea of what we’re about to see at any point in modern American history,” Hopkins said.