President Barack Obama spent a good portion of his press conference on Monday encouraging president-elect Donald Trump to reconsider some of his promises to dismantle what Obama described as the more successful accomplishments of the Obama administration, arguing that the American public would react badly if those things went away.

“My advice to him as I said when we had our discussions is that campaigning is different from governing. I think he recognizes that. I think he’s sincere in wanting to be a successful president and wanting to move this country forward,” Obama said, while noting he and the incoming Republican president have policy differences. “I don’t think any president ever comes in saying to himself, I want to figure out how to make people angry or alienate half the country. I think he’s going to try as best he can to make sure that he delivers, not only for the people who voted for him, but for the country at large. And the good thing is that there’s going to be elections coming up, so there’s a built incentive for him to try to do that.”

Obama said that he hoped Trump’s impulses to appeal to a broader segment of the U.S. population might be balanced with—and ultimately win out—over the core appeals he made to his conservative base on issues such as immigration, climate change, health care, and the Iran nuclear deal.

“I don’t think he is ideological, I think ultimately he’s pragmatic in that way,” Obama said. “That can serve him well as long as he’s got good people around him and he has a clear sense of direction.”

The president also characterized his conversation with Trump, a man who built his political career on challenging Obama’s legitimacy as president and as an American citizen through the false and racist birther conspiracy theory, last week as “cordial.”

“That didn’t surprise me to some degree because I think that he is obviously a gregarious person, he’s somebody who I think likes to mix it up and to have a vigorous debate,” Obama said.

While he said he had concerns about Trump’s stated policies, Obama argued that the federal government was an “ocean liner” not a “speedboat,” and that it would take significant work for Republicans to enact the key parts of their agenda that involved dismantling the Obama presidential legacy.

“It took a lot of really hard work to make significant policy changes, even in our first two years when we had larger majorities than Mr. Trump will enjoy when he comes into office,” Obama said.

He cited the Affordable Care Act and its providing insurance to 20 million people, promise of health care to those with pre-existing conditions, and allowance of children to stay on their parents’ health plan until the age of 26 as popular elements of his administration’s policies that might result in a backlash against the Republican Party and Trump if they were removed without being replaced with something better.

“My view is that if they can come up with something better that actually works and a year or two after they’ve replaced the Affordable Care Act with their own plan, that 25 million people have health insurance, and it’s cheaper and better and running smoothly, I’ll be the first one to say, “that’s great, congratulations,’” Obama said.

“If on the other hand whatever they’re proposing results in millions of people losing coverage and people that already had health insurance losing protections that were contained in the legislation, then we’re going to have a problem. I think that’s not going to be unique to me, I think the American people will respond that way.”

“The president elect rightly would expect that he’s judged on whether we improve from that baseline and on those metrics or things get worse,” he added, referring to the progress he argues his presidency has achieved in the last eight years. “And if things get worse, then the American people will figure that out pretty quick. And if things get better than more power to him and I’ll be the first to congratulate him.”

Obama also said that he was hopeful that Trump was sobered by the responsibility of entering office.

“Regardless of what experience or assumptions he brought to the office, this office has a way of waking you up. And those aspects his positions or predispositions that don’t match up with reality, he will find shaken up pretty quick because reality has a way of asserting itself,” he said. “And some of his gifts that obviously allowed him to execute one of the biggest political upsets in history, those are ones that hopefully he will put to good use on behalf of all the American people.”

During the course of the campaign, Obama said that Trump didn’t have the temperament to be president. He appeared to have modified that stance during his press conference on Monday.

“There are going to be certain elements of his temperament that will not serve him well unless he recognizes them and corrects them because when you’re a candidate and say something that is inaccurate or controversial, it has less of an impact then it does when you are president of the United States,” he said. “I think he recognizes that this is different and so do the American people.”

In terms of the Iran nuclear deal, Trump also offered that it might prove difficult, both practically and politically, to dismantle.

“To unravel a deal that’s working and preventing Iran from pursuing a nuclear weapon would be hard to explain, particularly if the alternative were to free them from any obligations and allow them to pursue a nuclear weapon,” Obama argued.

“For us to pull out would then require us to start sanctioning those other countries in Europe, or China, or Russia that were still abiding by the deal because Iran in their perspective had abided by the deal.”

Just because it might be difficult, disastrous, or even lead to war, though, doesn’t mean Trump won’t do it. John Bolton, who has been tipped as a likely candidate for secretary of state, in July told Breitbart’s Stephen Bannon, who was appointed on Sunday as chief strategist and senior counselor to the president, that the Iran deal was America’s “diplomatic Waterloo.”

“I think the Iranians have been violating this deal since before the ink was dry, and they’re on a path to nuclear weapons,” Bolton said at the time, contrary to available evidence, which Obama cited in his press conference on Monday, from Israeli intelligence officials (the Israeli government strongly opposed the deal, but its intelligence sources still say the Iranians haven’t violated it).

In a New York Post editorial published on Sunday, Bolton called on Trump to immediately “reverse the Iran deal and assert our interests.”Bolton was one of the chief backers of the Iraq War, which Trump claims he opposed, during the Bush administration when he was U.N. ambassador. If Bolton, who has consistently advocated for war with Iran, is appointed secretary of state, that will be a clear signal of the direction president elect Trump plans to take the country on foreign policy, and a sign that Obama’s hopefulness that Trump might reconsider some of the Republican Party’s more extreme policy positions, including one that might lead to a new war, is overly optimistic.