Donald Trump on first 100 days: It's a different kind of presidency

He has endured the steady drip of investigations and a seemingly endless churn of public drama.

"It's a different kind of a presidency," he said in an Oval Office interview as he approaches the key presidential benchmark of 100 days in office.

Mr Trump, who campaigned on a promise of instant disruption, indirectly acknowledged that change does not 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.

He was unclear 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.

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 capitalise upon the potent, and often fleeting, mix of political capital and public goodwill that usually accompanies their arrival in Washington.

Mr Trump, however, 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 January 20, his approval rating has hovered around 40% in most polls.

His early presidency has been dogged by FBI and congressional investigations into whether his campaign co-ordinated with Russians to tilt the race in his favour. It is a persistent distraction that Mr 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 his example, his two disputed travel ban executive orders are languishing, blocked by federal judges.

On Capitol Hill, majority Republicans muscled through Mr 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 Mr Trump's own party could not come together to fulfil its long-sought promise of repealing President Barack Obama's healthcare law.

HW Brands, a history professor at the University of Texas at Austin, said Mr 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".

Mr Trump would not concede that point, but he did acknowledge that being commander in chief brings with it a "human responsibility" that he did not much bother with in business.

"When it came time to, as an example, send out the 59 missiles, the Tomahawks in Syria," Mr Trump said, "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, Mr Trump cited "tremendous success" on an undefined strategy for defeating the so-called 'Islamic State' group and he talked at length about saving taxpayers hundreds of millions of dollars on the price of F-35 fighter jets.

It is too soon to say whether the presidency has changed Mr Trump in substantive ways. He has backpedalled on an array of issues in recent weeks, including his critiques of Nato, but his self-proclaimed flexibility means he could move back to where he started just as quickly.

He fires off tweets at odd hours of the morning and night, sending Washington into a stir with just a few words.

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

For the moment, Mr Trump seems to have clamped down on the infighting and rivalries among his top White House staff 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 does not get the credit it deserves for its work in a high-pressure setting.

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