The first in a three-part series

With gusto, Donald Trump promises to unwind President Obama’s governance with the stroke of his presidential pen and the support of a GOP-controlled Congress.

He can make good on those promises, but he will need to weather pushback from foes among the legislative branch, the courts, and voters and beneficiaries of Obama-era policies, plus world leaders who are wary of Trump’s worldview.

Waiting in the wings are advocates for progressive policies that were initiated over the last eight years. Eyeing some of the Cabinet appointees Trump has named, they expect changes that will run counter to the president-elect’s repeated vows during the campaign to support working people and their economic needs.

“We are well positioned to immediately bring transparency around what’s being done and to demand accountability of the Trump administration, and to bring forth the implications for everyday Americans,” said Carmel Martin, executive vice president for policy at the left-leaning Center for American Progress.

“He will have to answer for the hypocrisy based on his campaign proposals,” she said, if Trump and his agencies appear to be siding with wealthy Americans and big businesses and industries, as opposed to working-class voters who elected him. “There will be political consequences when he does that.”

Trump’s determination to tap his executive authority next year in all its many forms will demand sharp legal advice and patience. Some regulatory reversals he has in mind, for instance, are predicted to take two or more years to accomplish. Other Obama policies will be easier to erase. The Congressional Research Service recently provided Congress with a short road map, describing the least permanent executive actions of Obama’s tenure (executive orders, and department and agency directives and guidance), as well as the pending and even final rules that would take longer to jettison under provisions of the law.

In thinking about his prospective use of executive heft, Trump credited Obama with some of the how-tos.

“He’s led the way, to be honest with you,” Trump said of Obama when asked earlier this year if he’d govern through executive orders if elected president. “I won’t refuse it. I’m going to do a lot of things,” he said in an NBC News interview.

Trump’s overall rebuke of the 44th president, who for more than six years was pummeled by conservatives for what they argued was his unconstitutional interpretation of presidential authority, hinged on impact, not legality.

Trump argued he would emulate Obama’s techniques, but said he would take aim at the “right things.”

"I’m going to use them [executive orders] much better and they’re going to serve a much better purpose than [Obama’s] done." Donald Trump

“I’m going to use them [executive orders] much better and they’re going to serve a much better purpose than he’s done,” he said.

As experts have pointed out, Obama was a reluctant pupil while learning to advance his executive agenda while Congress balked on the sidelines. His tools went beyond executive orders, which are numbered, published in the Federal Register and can be revoked by a new president in a heartbeat. Trump has pledged to sign a flurry of E.O. policy reversals in January, as his predecessors did following changes of party control in years past.

In his final weeks in office, Obama is working to mitigate the impacts of the sea change his party expects.

On Tuesday, he flew to the U.S. Central Command in Tampa to deliver a final speech and unveil a report explaining the legal underpinnings for U.S. counterterrorism policies. Also on Tuesday, Trump set out to introduce retired Gen. James Mattis, his defense secretary-designate, at a rally in North Carolina, his first such effort to spotlight a Cabinet pick in person during a public event.

Obama believes some of Trump’s expressed boasts to undo existing initiatives are open to revision. The president-elect, for example, supported waterboarding during the campaign, a practice Obama and Congress banned as torture. Mattis disagreed with Trump about the utility of harsh interrogation techniques, an opinion the incoming commander-in-chief said “surprised” him during their recent discussions.

Trump also said during the campaign that he would consider targeting relatives of terror suspects. On waterboarding and the legal protocols established for drone strikes against terror suspects, Obama believes Trump will inevitably be influenced by the weight of the office and the strictures of law, by U.S. partners abroad, and by what the president described as Trump’s “pragmatic” bent.

Obama alluded to those hopes during his Florida speech, in which he defended his decisions and his record as commander-in-chief.

“No foreign terrorist organization has successfully planned and executed an attack on our homeland, and it’s not because they didn’t try. Plots have been disrupted, terrorists have been taken off the battlefield,” Obama told the military audience at MacDill Air Force Base. “We’ve respected the rule of law. We’ve enlisted our values in this fight.”

That fact, Obama said, is not a U.S. weakness, but “our greatest strength.”

With Trump in mind – a man Obama dubbed uniquely unqualified to lead the nation and its military – the president is using his final weeks in office to offer his by now seasoned perspective, which his successor solicited in a handful of recent telephone conversations.

"We live in a nation of laws, and these are laws that are applied that constrain the authority of the executive branch." White House spokesman Josh Earnest

“We live in a nation of laws, and these are laws that are applied that constrain the authority of the executive branch,” White House Press Secretary Josh Earnest said aboard Air Force One in advance of Obama’s remarks. “Hopefully, we will not encounter a situation in which the next administration or subsequent administrations run roughshod over those laws.”

During the last six years, Obama experimented with executive power as a kind of inducement to lawmakers to legislate during a period of divided government. Tighter gun background checks and criminal sentencing changes were both arenas in which the president believed there were like-minded GOP lawmakers serious about passing reforms. Initially, Obama used executive steps as examples to bolster his arguments for Congress to act. On gun safety and sentencing reforms, he failed to entice lawmakers to do so.

Obama also embraced the long reach of the executive branch while relying on his administration’s interpretations of existing law (for example, the Clean Air Act became the government’s tool to regulate coal-fired power plants). The administration promulgated regulations and revised rules linked to statutes already on the books (Treasury’s crackdown on corporate tax inversions, and the Labor Department’s increase this year in the salary threshold for workers to qualify for overtime pay, underscored Democrats’ progressive agenda).

And the administration selectively enforced laws, such as creating temporary work status for a category of undocumented immigrants already living in the country, and prosecutorial discretion at the Justice Department for recreational and medical use of marijuana as both became legal in more states.

Congress, with the power to legislate or appropriate away the president’s policy druthers, often ducked its role during Obama’s tenure, and instead turned to the judicial branch (and to the electorate) to try to settle political disagreements. One such example: A federal judge in Texas recently halted Obama’s expansion of overtime pay, which was estimated to benefit 4 million employees, ruling it exceeded the president’s authority. Advocates for the policy, which attracted criticism within the business community, anticipate the Trump administration will not defend the higher threshold for overtime pay in court.

Although there were cases where Obama sought to use his executive power to persuade Congress, there were far more instances when he was defiant and itching to confront Republicans on Capitol Hill.

Obama seized his executive heft as weaponry, expecting showdowns with his detractors in court or at the ballot box.

Before the election, the president told voters his agenda was at risk and would be eliminated by Trump. After the election, Obama searched for a rosier prediction, saying it would be politically challenging for the new administration to unwind the Affordable Care Act, immigration enforcement waivers, the Iran nuclear deal, and corporate and international commitments to curb reliance on fossil fuels, because each presented complex moving parts, eager beneficiaries, and geopolitical implications beyond the declarative simplicity of Trump’s campaign vows.

“There’s still a lot of stuff that sticks,” Obama said last month.

Alexis Simendinger covers the White House for RealClearPolitics. She can be reached at asimendinger@realclearpolitics.com. Follow her on Twitter @ASimendinger.