WASHINGTON (AP) — For nearly 100 days, President Donald Trump has rattled Washington and been chastened by its institutions.

He's startled world leaders with his unpredictability and tough talk, but won their praise for a surprise strike on Syria.

He's endured the steady drip of investigations and a seemingly endless churn of public personnel drama.

"It's a different kind of a presidency," Trump said in an Oval Office interview with The Associated Press, an hourlong conversation as he approached Saturday's key presidential benchmark.

Trump, who campaigned on a promise of instant disruption, indirectly acknowledged that change doesn't come quickly to Washington. He showed signs that he feels the weight of the office, discussing the "heart" required to do the job. Although he retained his signature bravado and a salesman's confidence in his upward trajectory, he displayed an awareness that many of his own lofty expectations for his first 100 days in office have not been met.

"It's an artificial barrier. It's not very meaningful," he said.

Trump waffled on whether he should be held accountable for the 100-day plan he outlined with great fanfare in his campaign's closing days, suggesting his "Contract with the American Voter" wasn't really his idea to begin with.

"Somebody put out the concept of a 100-day plan," he said.

One hundred days are just a fraction of a president's tenure, and no president has quite matched the achievements of Franklin D. Roosevelt, who set the standard by which all are now judged.

Still, modern presidents have tried to move swiftly to capitalize upon the potent, and often fleeting, mix of political capital and public goodwill that usually accompanies their arrival in Washington.

Trump has never really had either.

A deeply divisive figure, he lost the popular vote to Democrat Hillary Clinton and had one of the narrower Electoral College victories in history. Since taking office on Jan. 20, his approval rating has hovered around 40 percent in most polls.

Trump's early presidency has been dogged by FBI and congressional investigations into whether his campaign coordinated with Russians to tilt the race in his favor. It's a persistent distraction that Trump would not discuss on the record.

Furthermore, his three months-plus in office have amounted to a swift education in a world wholly unfamiliar to a 70-year-old who spent his career in real estate and reality television.

For example, his two disputed travel ban executive orders are languishing, blocked by federal judges.

On Capitol Hill, majority Republicans muscled through Trump's nominee for the Supreme Court, Judge Neil Gorsuch, but had to blow up long-standing Senate rules to do so. Then there was the legislative debacle when Trump's own party couldn't come together to fulfill its long-sought promise of repealing President Barack Obama's health care law.

H.W. Brands, a history professor at the University of Texas at Austin, said Trump is learning that "the world is the way it is for a whole bunch of complicated reasons. And changing the guy at the top doesn't change the world."

Trump won't concede that point.

But he acknowledged that being commander in chief brings with it a "human responsibility" that he didn't much bother with in business, requiring him to think through the consequences his decisions have on people and not simply the financial implications for his company's bottom line.

"When it came time to, as an example, send out the 59 missiles, the Tomahawks in Syria," Trump said of his decision to strike a Syrian air base in retaliation for a chemical weapons attack. "I'm saying to myself, 'You know, this is more than just like 79 (sic) missiles. This is death that's involved because people could have been killed. This is risk that's involved.'"

"Here, everything, pretty much everything you do in government involves heart, whereas in business most things don't involve heart," he said. "In fact, in business you're actually better off without it."

As for accomplishments, Trump cited "tremendous success" on an undefined strategy for defeating the Islamic State group. He talked at length about saving taxpayers hundreds of millions of dollars on the price of F-35 fighter jets. Trump held meetings during the transition and in the White House with the CEO of Lockheed Martin, which produces the F-35, but the cost-savings were already in the works when he took office.

He promised a tax overhaul plan that would give Americans a tax cut bigger than "any tax cut ever."

A man accustomed to wealth and its trappings, Trump has embraced life in the Executive Mansion, often regaling guests with trivia about the historic decor. With the push of a red button placed on the Resolute Desk that presidents have used for decades, a White House butler soon arrived with a Coke for the president.

It's too soon to say whether the presidency has changed Trump in substantive ways. He's backpedaled on an array of issues in recent weeks, including his critiques of NATO and his threats to label China a currency manipulator. But his self-proclaimed flexibility means he could move back to where he started just as quickly.

Stylistically, Trump remains much the same as during the campaign.

He fires off tweets at odd hours of the morning and night, sending Washington into a stir with just a few words. Trump still litigates the presidential campaign, mentioning multiple times during the interview how difficult it is for a Republican presidential nominee to win the Electoral College.

He is acutely aware of how he's being covered in the media, rattling off the ratings for some of his television appearances. But he says he's surprised even himself with some recent self-discipline: He's stopped watching what he perceives as his negative coverage on CNN and MSNBC, he said.

"I don't watch things, and I never thought I had that ability," he said. "I always thought I'd watch."

For the moment, Trump seems to have clamped down on the infighting and rivalries among his top White House staffers that have spilled into the press and created a sense of paranoia in the West Wing. He praised his national security team in particular and said his political team in the White House doesn't get the credit it deserves for their work in a high-pressure setting.

"This is a very tough environment," he said. "Not caused necessarily by me."

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Follow Julie Pace at http://twitter.com/jpaceDC