Donald Trump has always acted in the moment, with little regard for the past and proud contempt for the way things are usually done.

For half a century, he has believed that by refusing to be weighed down by precedent or procedure, he is liberated to come across as the brash truth-teller that the public craves. He has long said that he doesn’t care whether people believe he is dumb, ill-informed or a nasty rule-breaker; if his actions built up his bottom line, they were justified, he’d say.

Trump appears to have expected that his sudden and dramatic sacking of FBI Director James B. Comey on Tuesday might be greeted the way audiences relished his ritual firings of job applicants on his hit TV show, “The Apprentice” — as a sign of power serving truth, and in this case as a politically incorrect roundhouse punch that Republicans and Democrats alike would welcome.

[Trump liked Comey. Then he didn’t. Then he did. Then he didn’t. Then he fired him.]

If the president didn’t see that his precipitous firing of the man in charge of investigating the Trump campaign’s connections with the Russian regime might instead alienate some of his allies and outrage much of the public, that’s no anomaly. Rather, it’s an illustration of several of the president’s core character traits — a belief that the past doesn’t matter, a penchant to act swiftly and unilaterally, and a conviction that even the most unpopular actions can help build his brand.

1 of 28 Full Screen Autoplay Close Skip Ad × The scene in Washington after FBI Director Comey was fired View Photos President Trump’s firing of James B. Comey consumed Capitol Hill’s attention. Democrats slowed committee business in the Senate to protest the lack of an independent investigation into Russia’s election meddling, and Republicans saw rifts emerge as more questioned the president’s decision. Caption President Trump’s firing of James B. Comey consumed Capitol Hill’s attention. Democrats slowed committee business in the Senate to protest the lack of an independent investigation into Russia’s election meddling, and Republicans saw rifts emerge as more questioned the president’s decision. May 9, 2017 White House press secretary Sean Spicer speaks to reporters outside the West Wing after President Trump dismissed James B. Comey from his position as FBI director. Jabin Botsford/The Washington Post Buy Photo Wait 1 second to continue.

No one on either side of the aisle in Congress seemed to take seriously the administration’s argument that the president, who through much of last year led crowds in chants of “Lock her up,” was now suddenly sympathetic to the idea that Comey had inappropriately torpedoed Hillary Clinton’s campaign.

But while TV and social media immediately hauled out not-so-old clips of Trump singing Comey’s praises for reviving the investigation into Clinton’s improper use of an email server, the president insisted Wednesday that he’d fired Comey “very simply [because] he was not doing a good job.”

[Flashback to Nixon’s Saturday Night Massacre]

Trump has professed the belief that the public cares only about right now, and that only news reporters and his political opponents are bothered by ping-pong statements that take him from blasting Comey for going easy on Clinton, to praising him for getting tough on her, and on to firing him for having treated her unfairly.

“I think it’s startling that Democrats aren’t celebrating,” White House deputy press secretary Sarah Huckabee Sanders said Wednesday. She dismissed recitations of Trump’s praise for Comey last fall as irrelevant because he said those things last fall: “The president was wearing a different hat at that time,” Sanders said. He “was a candidate, not the president.”

Confronted with his past statements that stand in direct conflict with his current positions, Trump has always reacted not with remorse or embarrassment. Rather, a look of almost innocent surprise sweeps over his face and he says, as he has to reporters who remind him that he once promised to release his tax returns but then decided that he never would, “Nobody cares about this except you.”

“I’m just not interested in the past,” Trump has said. “I’m interested in the present.”

View Graphic With Comey's dismissal, the Russia investigation will soon be run by Trump allies

So when federal judges repeatedly reject Trump’s travel ban because of his campaign statements calling for a prohibition on Muslims coming into the United States, the president sounds angry but also flummoxed, as if those past statements don’t matter because they were said in the past.

[In travel-ban case, Trump’s lawyers are pressed to explain campaign statements. ]

Similarly, Trump has a long history of viewing larger issues through the prism of how they affect him. His letter to Comey dismissing the director made only one reference to a reason for the decision, a sentence that questioned Comey’s ability to lead the bureau but noted that “I greatly appreciate you informing me, on three separate occasions, that I am not under investigation.”

Trump’s persistent focus on himself, which he has characterized as “narcissism,” a trait he believes is vital for success in the business world, was an enduring source of humor and eye-rolling through his decades as a celebrity entrepreneur. But during his campaign, Trump said that as president he would turn the focus from himself to the American people.

Conceding that many of his vendors, employees and bankers suffered considerable losses when his businesses went through six corporate bankruptcies, Trump said that “for myself, these were all good deals. I wasn’t representing the country. I wasn’t representing the banks. I was representing Donald Trump. So for myself, they were all good deals. . . . When I was representing myself, even deals that didn’t work out were great deals because I got tremendous tax advantages. . . . I would walk away.”

As president, Trump promised, he would flip his priorities and represent the people. How would he make that pivot? “I’ll just do it,” he said.

Now, Trump faces a crisis in which Republicans and Democrats alike are questioning whether he is seeking the best possible management of the FBI or is instead trying to protect himself and his campaign staff from the prying eyes of investigators.

Almost by reflex, the language of Watergate resurged into Washington parlance after the Comey firing: Starting with comparisons to Richard M. Nixon’s “Saturday Night Massacre” — his firing of the special prosecutor who had been appointed to look into the Watergate scandal — the catchphrases of a four-decade-old scandal found new purchase: “What did the president know and when did he know it?” “The coverup is worse than the crime.”

[Is the Comey firing Nixonian or uniquely Trumpian?]

In moments of crisis, presidents tend to revert to the traits that got them to the pinnacle. Nixon, stubborn and righteous, dug in as the Watergate morass deepened. “Stonewalling,” it was called, and he repeatedly refused to give up the tapes and documents that investigators and the public demanded.

In 1973, at his first news conference after the Saturday Night Massacre, Nixon reflected on the media frenzy sparked by his decision. “It is true that to be under a constant barrage, 12 to 15 minutes a night on each of the three major networks for four months, tends to raise some questions in the people’s minds with regard to the president,” he said. “But now we must move on from Watergate to the business of the people.”

Echoes of that strategy resounded right after the Comey firing as the president’s aides tried to brush aside concerns about the Russia investigation.

“It’s time to move on,” Sanders said late Tuesday. “Frankly, it’s time to focus on the things the American people care about.”

Bill Clinton faced his crises by flitting from anger and denial to deeply personal confessionals — going on TV to concede “terrible moral error,” admitting to “causing pain in my marriage.”

That’s never been Trump’s style. Throughout his business career, and now in the presidency, he has proudly lived by simple mottos: Never look back. No regrets. When you’re hit, hit back 100 times harder.

Often, he would try to position a defeat as a victory, or he’d argue that he lost because he wasn’t really trying to win. In the last phase of his business career, Trump rented his name to products such as steaks, bottled water and mortgages. When some of those ventures went under, Trump said he bore no responsibility for any mismanagement.

“The mortgage business is not a business I particularly liked or wanted to be part of in a very big way,” he said after Trump Mortgage closed in 2007, leaving some bills unpaid.

At his darkest moments, such as when Trump faced financial ruin and a very public battle over his divorce, some business associates wondered how he managed to come to work each morning. But Trump showed no signs of distress: He “showed up every morning at 8 a.m.,” one of his top executives said, “tie tied, suit pressed, focused and moving forward.”

His family coat of arms, a regal symbol featuring a lion and a knight’s helmet, carries this Latin motto: “Numquam Concedere.”

“Never Concede.”