In the countdown to Inauguration Day, the guessing game over the presidency of Donald Trump continues. But there is one reality about the man who will become the 45th president on Friday. The Trump presidency will be a mold breaker. The question is whether he can run a successful presidency the same way he ran his campaign.

In almost all ways, the president-elect is breaking the conventions of presidential style. Given what happened in the campaign, this should hardly be a surprise, for Trump didn’t win the election by promising to continue past practices. In other words, always expect the unexpected.

His campaign was notable for the ways in which he eschewed what political professionals would have told him to do. He ran a lean operation in the primaries, insulted his rivals and others, thrived on controversy, ran few television ads throughout, adopted an unorthodox approach to debate preparation, embraced no consistent ideology, and on and on.

His supporters didn’t embrace him because they want continuity or business as usual in Washington. To the most passionate of his backers, the ways of Washington are stacked against them. They are tired of what they regard as an insiders’ game.

They found an unlikely champion in a billionaire developer who speaks a language they understand, rather than the political boilerplate generated from focus groups or messages that have been poll-tested and refined. Throughout the transition, Trump has given every indication he intends to remain true to the style that got him this far.

(Alice Li/The Washington Post)

Less than a week before he’s sworn in, Trump continues to shock and offend. He remains determined to litigate through Twitter and other means every grievance and slight, no matter whether large or small, presidential or not. He always wants the last word.

At the beginning of last week, he couldn’t resist attacking Meryl Streep after she attacked him during the Golden Globes. He called her “overrated.”

On Friday, as part of a morning tweet storm, Trump again attacked his defeated rival, Hillary Clinton, calling her “guilty as hell” for using a private email server as secretary of state. Was this his response to the news that the FBI would conduct an internal review of Director James B. Comey’s controversial handling of the email investigation?

[Signs of better relations with Russia under Trump]

On Saturday, he went after Rep. John Lewis (D-Ga.). The civil rights icon had announced that he would not attend Friday’s inaugural ceremonies, declaring that because of Russian interference in the election, he did not regard Trump as a legitimate president.

Trump belittled his critic and said Lewis’s district, which includes a significant portion of the proud city of Atlanta, “is in horrible shape and falling apart.” All of this was taking place on the weekend of the Martin Luther King Jr. holiday. Was this a fight Trump needed to take on?

It’s a long step from those kinds of outbursts to any rhetoric in an inaugural address about healing the country after the long, rancorous and divisive presidential campaign. But then, given his determination to take down the establishment and challenge the traditional ways of doing business, Trump’s real goal might not be any real attempt at reconciliation at all. Maybe he actually sees that as a fruitless exercise, given the country’s deep divisions.

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Trump also is upending tradition on matters of conflicts of interest, having announced this week that he will not divest himself of his business. He pledged to put in place safeguards to avoid conflicts, but ethics experts say the steps he has taken are not sufficient. Trump seems unconcerned by the complaints.

Trump’s policy priorities remain the same as he outlined in the campaign: building a wall on the U.S.-Mexican border, repealing and replacing the Affordable Care Act, ending or renegotiating various trade deals, taking down the Islamic State. The details of that agenda, however, remain murky, especially after a week of testimony by his Cabinet nominees, where the disagreements between Trump and those nominees played as an almost continuous loop.

They and he seem to have big disagreements on whether the Russians are adversaries to be confronted or potential partners to be courted. But they disagree on other areas, too — trade or torture or nuclear weapons for Japan or what to do with the Iranian nuclear agreement.

Trump told reporters Friday at Trump Tower that he has no problem with the apparent conflicts with his advisers-to-be. “I told them, ‘Be yourselves and say what you want to say. Don’t worry about me,’ ” he said. “And I’m going to do the right thing, whatever it is. I may be right, and they may be right. But I said, ‘Be yourself.’ ”

That might be a refreshing change from past administration efforts to stage-manage everything from the White House. Or it could suggest a disorderly or even chaotic decision-making process in the new administration, one in which the White House and key Cabinet officials are at war with one another, especially on matters of national security.

[High expectations meet the ways of Washington]

It also leaves open the question of who the real decision-makers will be in a Trump administration, beyond the president himself. Will his picks for secretary of state and secretary of defense and the CIA and national intelligence director hold sway? Or will the true influentials be those in the White House inner circle, among them son-in-law Jared Kushner and chief strategist Stephen K. Bannon or national security adviser-designate Lt. Gen. Michael Flynn?

Of all the ways in which Trump appears committed to breaking with current policy and custom is his approach to Russia. In a Wall Street Journal interview, he hinted that he is open to lifting the sanctions imposed on the Russians in retaliation for Russian hacking and other interference in the election. He said that he would keep them in place for a time but could shift if Russia appears cooperative in the fight against terrorists.

Trump won the election by winning an electoral college majority. But he enters the White House under a Russian cloud, given the intelligence community’s conclusions that Russian interference was expressly done to harm Clinton and thereby help Trump win the election.

Trump finally conceded last week that the Russians were behind the hacking, but plenty of other questions remain about what happened, how what happened affected individual voters, and what relationships, business or otherwise, Trump might have with Russians that could affect his thinking as president. The pursuit of answers will continue on Capitol Hill and elsewhere. Trump cannot wish them away.

Much remains to be learned about how Trump sees U.S.-Russian relations. Is his approach focused primarily on getting the Russians to play a constructive role in the fight against the Islamic State? Or does this fit into a vision of a world in which populist movements in Europe do battle with the existing establishments?

Friday’s inaugural ceremonies at the Capitol will be marked by traditional pomp and circumstance. Trump will ride to the Capitol with President Obama, after meeting him at the White House, as has been the custom. The inaugural luncheon and parade will follow. That should be enough to humble anyone, as the transfer of power is carried out.

After that, it will be Donald Trump’s presidency, to do with as he sees fit. History and past practice and the burdens that come with the office could begin to change him. But he has given every indication that his will be a presidency unlike any the country has seen in a long time — Trumpian in all respects and therefore unpredictable in approach and outcome.