"Regulations have grown into a massive job-killing industry. The regulation industry is one business I will absolutely put an end to on day one," Trump said during an economic speech in New York earlier this month.
Trump has also pledged to unwind Obama's immigration policies on his first day, including having the "first piece of paper that I'm going to sign" be an order to get rid of criminal undocumented immigrants. He has also pledged to repeal "every single Obama executive order," "repeal Obamacare" and "end the war on coal," according to his running mate, Indiana Gov. Mike Pence. His transition chair, New Jersey Gov. Chris Christie, has told lobbyists in private meetings in DC that the transition team is focused on reviewing administration policies to look for everything that can be rolled back.
Experts and veterans of the executive branch say, however, there's a big gap between what is theoretically possible and what is realistically doable.
"I'd say be careful what you target first," Former George W. Bush regulatory chief Susan Dudley said of the expectations game. "I think there could be large reforms, especially working with Congress, but recognize that that will take years, not 100 days."
There are tiers of executive actions, each of which have different relative permanency.
The easiest kind to roll-back is executive orders. Those merely require an executive order to take them back, and in fact Trump could issue a blanket order that rolls back every executive order Obama signed on the first day of his presidency, if he wanted to. He could also order every agency to begin a process of replacing the rules of the previous administration.
Another quick option is to halt any rulemaking that has not been finalized. Formal regulations require a process before being put into place, and any that have yet to become final before the start of Trump's term could be ordered halted.
Trump could also make selective enforcement decisions, giving guidance to his agencies to not enforce rules on the books, such as environmental regulations.
But for any rule that has been finalized, it requires an entirely new process to revoke it or change it. Best case scenario, the process takes a few months, and can stretch for years. For any regulation, by law, an agency must have a formal proposal, based on a review of the status quo; must open that proposal for a public comment period (which can generate hundreds of thousands of comments on meaningful policy); must review all the substantive comments and issue a final rule that responds to the substantive comments. And then there can be litigation from opponents as well as an inter-agency process to coordinate any overlapping jurisdictions.
There is one nuclear option for rules finalized in what's known as "midnight regulations," or those that are made final in the waning months of an administration. If Trump were to enter office with a Republican House and Senate, under the Congressional Review Act, lawmakers could pass a resolution of disapproval on any recent rule that would nullify the policy. The move has only been used once in history, by Bush to nullify a workplace ergonomics regulation from the Bill Clinton administration.
But even the processes that seem simple still take complex work to execute. Former administration officials warn incoming presidents to be realistic about what they hope to achieve.
Dudley, an expert on regulatory policy at George Washington University, said it would also be "not very advisable" to repeal previous executive orders in one fell swoop, because it would carry substantial consequences.
As for ordering agencies to go over all previous rules: "It's a tedious process to go through all of that, and there are a lot of other things in government that you couldn't spend the resources on if you were to look at every single regulation."
In addition to the technical hoops to jump through, policy experts also warn of the environmental factors of changing rules. Every policy in place will have its supporters, and after eight years of an administration, industries and individuals will have already organized around the rules.
"The regulations are already in the bloodstream of lives and the economy, they've been on the books for a while, and it's hard to pull particular drops of blood out of the bloodstream," said Michael Greenstone, a University of Chicago professor and former Obama administration economic and energy adviser.
Any rulemaking would also bring in an avalanche of feedback from stakeholders.
Lanhee Chen, a former policy expert for Mitt Romney's 2012 campaign and transition, is a proponent of a new president being able to unwind the previous administration's policies. But he acknowledged that people's responses to existing regulations add difficulty. "'We've started to comply with this and we prefer certainty over non-certainty,' we heard that a lot," Chen said.
Akin Gump partner Hal Shapiro, a former senior adviser in the Clinton administration, said it's important to remember what is possible is not always doable.
"There is a tremendous disconnect between theory and practice here," Shapiro said. "If the president of the United States has the constitutional authority to change guidance or an executive action, they will almost always prevail. But the reality of it is much harder."
Obama created opening
In some ways, Obama has paved the way for his successor to undo his work more easily, both conservative and liberal policy experts agreed.
The Obama administration has generated an unusually large amount of policy outside of the typical rulemaking process, meaning all of it can be undone in the same way.
"It would be the great irony of the Obama administration if, especially if the Republicans retake the White House, President Obama and his administration spent eight years really making use of the non-notice-and-comment procedures for getting rules in place, and the great irony would be if a new president came in and in the same assertions of power to undo all that," said Adam White, a research fellow at the conservative-leaning Hoover Institution.
White cited a number of Obama policies, including much of his immigration agenda and guidance like a controversial directive on transgender bathrooms.
Shapiro also warned that given Obama's use of executive orders and guidance, a new president with a different agenda could have "enormous consequences."
"I think the President has taken extraordinary measures, particularly in the second term, that were done through executive action and not regulation, and theoretically almost every single one of those could be reversed through executive action," Shapiro said. "How quickly as a practical matter could this be done? Each one is different, each one has a different complexity and legal requirements that have to be attended to. But as President, it's in their power to do. And if they want to do it, it's hard to stop them. It's all on the table."
Obama, for his part, has made his campaigning on behalf of Democrat Hillary Clinton personal, saying his legacy is on the line.
"I will consider it a personal insult -- an insult to my legacy -- if this community lets down its guard and fails to activate itself in this election," he recently told