President Barack Obama meets with President-elect Donald Trump in the Oval Office of the White House in Washington, D.C., Nov. 10, 2016. (Kevin Lamarque/Reuters)

President Obama says President-elect Donald Trump was an “unconventional candidate” who ran an “improvisational campaign.” But he doesn’t think that approach will work in the White House.

In an interview that aired on “60 Minutes” Sunday, Obama was asked if it’s possible for Trump to run “an improvisational presidency.”

“I don’t think so,” Obama said. “And so now he’s in the process of building up an organization. And we’ll have to see how that works. And it’ll be a test, I think, for him and the people that he’s designated to be able to execute on his vision.”

But Obama says it would be a mistake to “underestimate the guy, because he — he’s going to be 45th president of the United States.”

“The one thing I’ve said to him directly, and I would advise my Republican friends in Congress and supporters around the country, is just make sure that as we go forward, certain norms, certain institutional traditions don’t get eroded,” Obama said. “Because there’s a reason they’re in place.”

Obama also gave rare props to the tea party.

“I give them credit for having activated themselves,” he said. “And they made a difference in terms of moving the Republican Party, in terms of moving the country, in a particular direction. It’s a direction I disagreed with. But it showed that, in fact, you get involved, if your voice is heard, it has an impact.”

“Do you feel the same way about Donald Trump?” CBS’s Steve Croft asked.

“Well, I think that he clearly was able to tap into a lot of grievances,” Obama replied. “And he has a talent for making a connection with his supporters that overrode some of the traditional benchmarks of how you’d run a campaign or conduct yourself as a presidential candidate.

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“What will be interesting to see is how that plays out during the course of his presidency,” he continued. “We are moving into an era where a lot of people get their information through tweets and sound bites and some headline that comes over their phone. And I think that there’s a power in that. There’s also a danger, what generates a headline or stirs up a controversy and gets attention isn’t the same as the process required to actually solve the problem.”

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The president, who leaves office Friday, says he has very few regrets and is proud of the things he was able to change.

“We’re probably the first administration in modern history that hasn’t had a major scandal in the White House,” Obama said. “In that sense, we changed some things.”

But he said he is frustrated with what he wasn’t able to change — specifically, the gridlock in Washington.

“In the first two years, when I had a strong majority in the House and the Senate, we were as productive as any administration has been since the ’60s,” Obama said. “But to sustain a governing majority, that requires an ability for Republicans and Democrats to find some common ground. And right now, the structure of the system is such where it makes it really hard for people to work together.”

One thing in particular clearly bothers Obama: the GOP’s refusal to consider his final Supreme Court nominee, Merrick Garland.

“I mean, the fact that Mitch McConnell, the leader of the Republicans, was able to just stop a nomination almost a year before the next election and really not pay a political price for it — that’s a sign that the incentives for politicians in this town to be so sharply partisan have gotten so out of hand that we’re weakening ourselves,” Obama said.

“We couldn’t even get a hearing,” the president said. “Trying to get the other side of the aisle to work with us on issues, in some cases, that they professed, originally, an interest in, and saying to them, ‘Hold on a second. You guys used to think this was a good idea. Now just because I’m supporting it, you can’t change your mind.’ But they did.”

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Obama said he wishes he could have taken a “mulligan” on the online rollout of the Affordable Care Act, his signature health care law, better known as Obamacare.

“You know, if you know you got a controversial program, and you’re setting up a really big, complicated website, [the] website better work on the first day or first week or first month,” he said. “The fact that it didn’t obviously lost a little momentum. That was clearly a management failure.”

The president also acknowledged that the “red line” comment he made in a 2012 speech about Syria using chemical weapons, which he said was not in his prepared remarks, created problems for the United States in the Middle East — but he added that he does not regret saying it.

“Look, if you’re putting all the weight on that particular phrase, then in terms of how it was interpreted in Washington, I think you make a legitimate point,” Obama said. “I’ve got to tell you, though, I don’t regret at all saying that if I saw [Syrian President] Bashar al-Assad using chemical weapons on his people, that that would change my assessments in terms of what we were or were not willing to do in Syria.

“I would have I think made a bigger mistake if I had said, ‘Eh, chemical weapons. That doesn’t really change my calculus,'” Obama continued. “I think it was important for me as president of the United States to send a message that, in fact, there is something different about chemical weapons.”

At 55, the 44th president said he may look older than he did when he took office, but added, “Physically, I feel probably as good as I’ve ever felt — and I’ve got as much energy as I ever did.”

Still, Obama said he plans to get some much-needed rest beginning Saturday, the day after he leaves office.

“I’m not setting my alarm,” Obama said. “That, I’m certain of.”

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