Donald Trump could erase Obama's legacy almost as soon as he takes office

President-elect Donald Trump's victory on Election Day has put some of President Barack Obama's hallmark achievements in jeopardy.

Trump has come out strongly against almost all of the top initiatives Obama spent eight years working on - the Asia pivot, the Trans-Pacific Partnership trade pact, Obamacare, and the Iran nuclear deal - and they're fragile enough that Trump could reverse course fairly easily.

"You have an outsider president being replaced by the most outsider candidate ever elected," Ian Bremmer, a geopolitical analyst and president of the Eurasia Group, told Business Insider via email.

"There's nothing like one upsmanship, big league, to destroy your legacy."

Iran nuclear deal

Trump has called the Iran deal one of "the worst deals ever made by any country in history" and threatened to rescind or renegotiate the agreement that gives Iran sanctions relief in exchange for curbing its nuclear program.

"Trump has repeatedly slammed the deal as being a bad deal - the assumption is that he's going to do something," Jonathan Schanzer, a Middle East expert who is a vice president of research at the Foundation for Defense of Democracies, told Business Insider after the election.

Schanzer also admits that given Trump's ambiguity on the subject, it's "extremely difficult" to anticipate how negotiations would play out.

After the election, Iran's foreign minister Mohammad Javad Zarif has called on Trump to stick to the agreement. And in June, before Trump had officially become the Republican nominee for president, Zarif said Iran would reject any attempt from the US to renegotiate the deal.

It "is not an Iran-US agreement for the Republican frontrunner or anybody else to renegotiate," he said. "It's an international understanding annexed to a [United Nations] Security Council resolution."

Bremmer said he's skeptical about whether Trump will actually upend the deal. But even if he didn't, his administration will likely dilute the image of the Iran nuclear deal as a bright spot in Obama's presidency.

The Trans-Pacific Partnership and Asia pivot

While much of Obama's foreign policy doctrine has been consumed by wars in the Middle East, a pivot to Asia was supposed to be a prominent part of Obama's legacy.

But since Obama's final trip to Asia as president turned out to be a bit of a disaster, that legacy looks to be uncertain.

And Trump winning the presidency means that Obama's controversial trade deal is likely dead in the water.

"Trump's victory kills the [Trans-Pacific Partnership] and replaces it with 'America First,'" Bremmer said. "China sees this as its moment to seize primary leadership in Asia."

The Trans-Pacific Partnership would lower tariffs for 12 countries around the Pacific, not including China. Obama was hoping to get the deal through Congress during the lame-duck period before he leaves office, but that now seems highly unlikely.

Trump is also unlikely to continue Obama's pivot to Asia, considering his campaign-trail rhetoric about putting American interests above all else.

Obamacare

On the campaign trail, Trump often expressed the desire to repeal and replace the Affordable Care Act, known colloquially as Obamacare.

He has called Obamacare a "total disaster" and promised to replace it with "the finest healthcare plan there is."

But since the election, he has softened that position, saying he'd be open to amending it instead.

And in any case, even Republican leaders admit that repealing the Affordable Care Act would be difficult.

"Domestically there's much more of Obama's legacy that will stay intact, likely including some piece of his most controversial policy, Obamacare," Bremmer said.

Alex Lockie contributed to this report.