President Donald Trump speaks in the Oval Office at the White House on Sept. 25. (Jabin Botsford/The Washington Post)

As a businessman, Donald Trump erected unauthorized flagpoles on his properties to embarrass local officials who were trying to uphold zoning ordinances. As a presidential candidate, he told the first football player who sat in protest during the national anthem to "find another country." And as president-elect, he attempted unsuccessfully to revive the decades-old debate about the constitutionality of flag burning, after a single incident at a small college in Massachusetts.

So when he decided, out of the blue, to attack the National Football League over its players' protests during the national anthem, the resulting controversy followed a well-worn formula. What was different, however, was the enormous backlash that his comments created — far larger than any of those previous incidents combined.

Trump attacked an enormously popular sport whose fans prefer it to be a politics-free arena, while once again touching on the raw nerve of race. In so doing, the president proved anew that divisive provocations can mean something completely different when they come not from a private citizen, but the man whose very job description is to lead the country.

"Most presidents believe that a big part of their job is to keep the country together," said Michael Beschloss, a presidential historian, who noted that even Richard M. Nixon spoke of bringing the nation together during his 1969 inauguration. "There is very little sign that Donald Trump has much of an idea that unifying this country has much to do with being president. He just hasn't shown it."

Trump credits his ability to see and exploit cracks in American society as the key to his political success. During the campaign, he praised his gut instinct in latching onto fears about Muslim refugees and Hispanic immigration as the key to his victory in the Republican primary, comparing it to his ability to predict successful real estate investments.

"I understand people," he said before another rally in Alabama in 2015. "I've made a lot of money because of people, because deals aren't anything other than people."

But those same instincts may be tripping him up as president. While it's not clear what the ultimate effect of sticking to old habits will be for his presidency, his rejection of the unifying traditions of the White House has already had a clearly negative effect on his political support. A recent Washington Post-ABC News poll found that 66 percent of Americans say Trump has done more to divide the country than unite it, up from 49 percent in the same poll shortly after the election in November. The new poll, which was conducted Sept. 18 to 21, before the NFL controversy, found that 57 percent of the country disapproves of his job performance.

Trump started the latest controversy Friday by using a crude epithet to describe football players who kneel in protest on the field during the national anthem. The comments echoed far beyond political circles, effectively unifying the most popular sports league in the country against him. Players linked arms in defiance, the number kneeling during the anthem skyrocketed, 30 of the 32 team owners released statements calling for unity, and millions tuned in to watch an array of sportscasters and athletes offer public condemnations of the president's position.

"I would say he should apologize," NBC color commentator Chris Collinsworth said before "Sunday Night Football," the top-rated show on broadcast television. "They're not SOBs. They're smart, thoughtful guys."

Trump seemed initially to welcome the attention on Sunday, retweeting posts from those who supported his position and escalating his campaign with the retweeted hashtags #StandForOurAnthem and #BoycottNFL. But he also showed signs of discomfort at the resulting firestorm, telling reporters later in the day that he was not calling on supporters to boycott the NFL. "They can do whatever they want," he said.

He argued, in a separate tweet, that players who locked arms during the anthem were doing something "good," even though those same players said they were demonstrating their unity against the president's statements. And he returned to his habit of rebroadcasting, and exaggerating, the support he has received for his position.

"There was tremendous solidarity for our flag and for our country," he told reporters about Sunday's football games, which featured more protests during the anthem than ever before.

The White House on Monday sought to soften the president's controversial comments.

"Celebrating and promoting patriotism in our country is something that should bring everybody together," White House press secretary Sarah Huckabee Sanders said. "This isn't about the president being against something. This is about the president being for something."

Trump's political strategy appears to be following the logic of other national firestorms he has prompted: take a stand for a position that brings into clear relief the divide between himself and those who he describes as unpatriotic elites. He uses the controversy to dominate the news cycle, position himself as a strong leader and demonstrate that he is fighting for regular working Americans nostalgic for an earlier time in the country's history.

At a campaign rally for Sen. Luther Strange (R) on Friday in Huntsville, Ala., Trump previewed the gains he foresaw by denouncing players who voiced political opinions on the field. The first owner who bans players from protesting on the field "will be the most popular person in this country," he suggested, giving political advice that only he has taken so far.

Trump's longtime instincts tend to come to the fore when he is looking to distract from other issues. Shortly after his attorney general recused himself from the Russia investigation, Trump decided to rattle the government with a false claim that President Barack Obama had wiretapped Trump Tower during the 2016 presidential campaign. The most recent attack on the NFL came as he stares down two potential blows to his presidency this week, the likely failure of another Senate plan to repeal and replace the Affordable Care Act and a special primary election in Alabama, where his chosen candidate, Strange, continues to trail in the polls.

There is little question that fights over the flag helped Trump when he was a private citizen and then as a candidate. On his golf courses, he has used flags — typically giant ones on poles as tall as eight stories — as a way of shaming local authorities with whom he has tangled over other issues. He put up one on a California course, refusing to pay the required permitting fee, and another at his Mar-a-Lago estate in Palm Beach, Fla., in clear violation of local rules. In both cases, he publicly argued that local officials were unpatriotic, even though they were only following regulations. "The town council of Palm Beach should be ashamed of itself. They're fining me for putting up an American flag," Trump fumed to the news media.

"It was a huge win for him when he took on the town of Palm Beach with the flag," said Christopher Ruddy, a friend of Trump who is a member of his club at Mar-a-Lago. "It was a win because it got a lot of attention." In the end, Trump settled with the community, agreeing to make a donation to charity in lieu of a fine, and to reposition the flag on a slightly smaller pole. In California, the local city council eventually granted retroactive approval for his golf course flag.

During his presidential campaign, he repeatedly used respect for the flag as a stand-in for his own connection to his supporters, mocking those who disrespected it as un-American elites. "Total disrespect for the American flag," Trump said at a Greensboro, N.C., rally in October, after a protester held up a flag upside down and began shouting. "That's what's happening to our country."

A few weeks earlier, when Colin Kaepernick, then a quarterback for the San Francisco 49ers decided to sit for the national anthem before games in protest of racial inequality, Trump had a quick rejoinder. "I think it's a terrible thing," he said.

Those comments were quickly forgotten in the quick-moving presidential campaign. But Trump returned to them weeks after his election, when a flag at Hampshire College in Amherst, Mass., was burned by an unknown vandal as it hung on a campus pole. Trump's response was to propose new consequences for a form of protest that the Supreme Court ruled in 1989 is protected under the Constitution.

"Perhaps a loss of citizenship or a year in jail!" the president-elect tweeted.

The crusade never caught on, and it quickly faded from public attention. Seven-and-a-half weeks later, Trump was sworn in as the 45th president.