For many of his supporters, as a candidate Donald Trump’s appeal was his style. His substance was an afterthought. To be sure, Trump had a platform — a border wall, renegotiate trade deals, a stronger military, repeal Obamacare, lower taxes and so on.

But it was Trump’s style that won over a lot of people. Finally, here was a candidate unafraid of the media. He praised America. And he promised big.

Trump’s “promise big” strategy, however, was not new. He revealed it three decades ago in his best-selling book “The Art of the Deal.”

“The final key to the way I promote is bravado,” Trump wrote in the book. “I play to people’s fantasies. People may not always think big themselves, but they can still get very excited by those who do. That’s why a little hyperbole never hurts. People want to believe that something is the biggest and the greatest and the most spectacular. I call it truthful hyperbole. It’s an innocent form of exaggeration, and a very effective form of promotion.”

We’re just past the 100-day mark of the Trump presidency. Things haven’t gone exactly as planned. Trump had to cave on some of his promises including the repeal of Obamacare and the beginning of the construction of the border wall.

As Trump learned, it turns out you can’t just will Congress to do what you want, even if it is Republican controlled.

For now, this hasn’t tarnished Trump in the eyes of his supporters. A Washington Post-ABC poll conducted last month shows only 3 percent of Trump voters have buyer’s remorse. In addition, that same poll showed supporters of Hillary Clinton, Trump’s opponent in the 2016 election, regretted voting for her.

Despite a barrage of negative media coverage since Election Day, that particular poll suggested Trump would have won by a bigger margin than he did last November, perhaps even winning the popular vote if the election were held today.

That doesn’t change the fact that Americans still view Trump unfavorably. He is a president with the lowest approval numbers at this stage of his term. To deliver on those campaign promises, he’s going to have to turn his approval rating around.

Ronald Reagan was a successful president because he took his message to the American people. He made it difficult for Democrats to oppose him, and ultimately they went along with some of his policy efforts.

As it stands right now, Democrats are fundraising on the basis of their opposition to Trump in every possible way — his Cabinet picks, Supreme Court nomination, executive orders and any and every legislative effort.

If he is successful in correcting his approval ratings, it will be more difficult for his opponents to be obstructionists.

One of the problems Trump faces is that he has to prove his campaign promises were not just hollow exaggerations and that he intends on trying to fulfill them. If he promised a border wall, but it turned out to be just a wild claim to get people to vote for him, those opponents will be quick to point that out.

“He promised a border wall. He promised to get the economy back on track. He promised to make us all safer. But he didn’t. He just wanted your votes, so he lied to you. Vote [insert Cory Booker, Elizabeth Warren, Joe Biden], Democrat for president.”

It’s not clear how long Trump can go on without delivering at least some of the goods. He does have the benefit of a very loyal core group of supporters, and if he holds onto them it will be very difficult for Democrats to unseat him in 2020.

Trump said in January of last year, “I could stand in the middle of Fifth Avenue and shoot somebody and I wouldn’t lose any voters.”

Yes, that’s an exaggeration, but it illustrates how difficult it will be to erode his support. With Trump, it is not having the most supporters but about having the most enthusiastic supporters. Yes, most Americans don’t like him. But the ones that do will wait in line and vote for him while many of his detractors might sit around and complain — but that will be the extent of their political activism.

Case in point: There was actual audio of Donald Trump boasting about grabbing women by their genitals. That would have finished off the hopes of a lot of candidates. But with his supporters being so personally invested in his success, it did not make much of a difference in the end.

He ultimately will have to show some progress. As he also says in “The Art of the Deal,” you have to deliver the goods.

“You can’t con people, at least not for long,” Trump wrote about his “truthful hyperbole.” “You can create excitement, you can do wonderful promotion and get all kinds of press, and you can throw in a little hyperbole. But if you don’t deliver the goods, people will eventually catch on.”

It’s still early. But rest assured if you are one of his supporters, Trump knows he will have to deliver if he wants voters to view him as a good president and politician.