WASHINGTON — A few hours before Mississippi Sen. Cindy Hyde-Smith's debate with Democratic challenger Mike Espy last month, at a time when Republicans were taking a hit to their brand because of her remarks about attending a "public hanging," President Donald Trump called the freshman lawmaker with an admittedly awkward request.

Trump urged her to apologize, two Republicans briefed on their conversation told NBC News. As political wisdom, the advice itself was unremarkable, except for its source: a man who — as he acknowledged to Hyde-Smith during the call, one of the sources said — doesn't follow it. At all.

That tendency may have made him an imperfect messenger, he conceded — but as he laid it out, he was the exception that proved the rule: he didn't have to apologize. Ever. But she did.

Hyde-Smith, well aware that Trump still had two planned campaign stops to make for her, did as she was asked. She scrambled to put together a carefully crafted statement for the debate and then offered a qualified apology on stage.

There's little reason to think the episode affected the outcome of the election — Hyde-Smith won by 8 percentage points — but it highlighted the tension between Trump's personal code of conduct and what some view as the best way for him, and for his party, to appeal to persuadable voters he's alienated as he seeks re-election: Admit errors — and use that exercise to reach out to a broader audience.

That process could be his best shot at reclaiming swing voters who gave him the benefit of the doubt two years ago, but have since become disenchanted. It's also completely antithetical to the political instincts that have served Trump well with his base.

"His general philosophy is you get no credit for an apology, so don’t do it," said one person who advised Trump's 2016 campaign.

Trump is viewed as only ever apologizing once during his political career — after the October 2016 release of an "Access Hollywood" out-take in which he could be heard saying that he liked to grope women without their consent. But even that mea culpa rates an asterisk.

Trump, speaking direct to camera, called his remarks "locker room" talk. He then went on the attack.

The performance was evidence, the campaign adviser said, of Trump "succumbing to every single person around him" in agreeing to issue a semi-apology.

"He even turned that into 'this isn’t an apology,'" the adviser said.

But Doug Schoen, a former adviser to President Bill Clinton and a Fox News contributor, said that while Trump's approach worked against Hillary Clinton, he now needs to change tacks, reach out beyond his political base and compromise. Part of that process, he said, is acknowledging mistakes.

"His base is now too small and eroding too quickly to govern effectively and win re-election," Schoen said. "People respect politicians who acknowledge they can make mistakes."

With Trump's job approval sitting at 39 percent in the latest Gallup poll, there's little question that he has plenty of room to improve his standing with the American public before voters go to the polls in November 2020.

Backtracking, but never saying 'I'm sorry.'

There are a few corollaries to Trump's no-apologies policy. One is that Trump often reverses course or alters his direction without pausing to say that he was wrong in the first place.

On his signature issue, a border wall with Mexico, he made a handshake deal last year with congressional Democrats to permanently extend protections for undocumented immigrants brought to the U.S. illegally as children in exchange for full funding of the wall, only to back out and issue a spate of new demands for limiting legal and illegal immigration.

The impasse ultimately resulted in a partial government shutdown Dec. 21 that remains in effect. With the clock ticking down, Senate Republicans passed a measure to avoid a shutdown that did not include Trump's $5 billion request for wall funding because they believed the House would clear it and Trump would sign it.

But when Trump felt pressure to stand up for the wall from conservative commentators — and his political base — he promised that he would not sign the bill, prompting the shutdown.

He didn't apologize to Senate Republicans, to conservatives who initially thought he was about to double-cross them or to the federal workers and American citizens affected by the shutdown.

Indeed, as Trump demonstrated again in the second year of his presidency, he's much happier to change direction than dwell on a miscue.

Rather than apologize to American farmers for starting a trade war with China that led to economic pain in the heartland, Trump bucked Republican orthodoxy and authorized massive subsidies for growers.

Instead of telling British Prime Minister Theresa May that he was sorry for telling the London tabloid "The Sun" that she had "wrecked" Brexit during a critical phase for one of her proposals for executing the withdrawal of the U.K. from the European Union, Trump told her that not everything he said had been reported — and they both blamed the media.

"When I saw her this morning I said 'I want to apologize. I want to apologize, because I said such good things about you,'" he told reporters. "She said, 'don't worry, it was only the press.' I thought that was very professional."

He was adamant earlier this year that no one in his White House should apologize after aide Kelly Sadler reportedly said that then-Sen. John McCain's opposition to the president's nominee for CIA director, Gina Haspel, was of little consequence because the Arizona Republican was "dying anyway."

When McCain died, Trump refused to put American flags at half staff for his frequent critic until veterans groups shamed him publicly.

In the wake of mail bomb deliveries and a synagogue shooting in the run-up to the midterm elections, Trump did briefly back away from many of the highly personalized political attacks that were a staple of his barnstorming speeches — even as he told reporters that he might escalate his political rhetoric.

The off-beat apology

There's another proviso to Trump's no-apologies policy. Trump has been known to say that he is sorry, or that he apologizes. It's just not usually directed at those he's offended — and sometimes, the regrets are delivered with a sarcastic edge that relays the opposite message.

For example, he apologized "on behalf of the American people" to Supreme Court Justice Brett Kavanaugh, who was confirmed after Christine Blasey Ford testified before the Senate Judiciary Committee that Kavanaugh had sexually assaulted her when they were in high school — a charge Kavanaugh denied.

Trump has said he doesn't regret mocking Ford on the stump during a rally in Southaven, Miss., because Kavanaugh won confirmation.

On the other hand, Trump has mockingly apologized to "Pocahontas," the nickname he's ascribed to Sen. Elizabeth Warren, D-Mass., because she has claimed Native American heritage.

"Pocahontas, I apologize," Trump said at a campaign rally in July in what would become a familiar line. "To you, I apologize. To the fake Pocahontas, I won't."

Earlier in the year, Trump had referred to Warren as Pocahontas during a White House ceremony honoring Native Americans, drawing stern rebukes from Native American groups.

For that, he did not apologize.

Rick Tyler, a Republican strategist who worked on Sen. Ted Cruz's 2016 Republican presidential primary campaign and a frequent Trump critic, said he thinks there are two drivers behind Trump's general unwillingness to apologize that both come down to ego.

"It's his worldview, and the way that he looks at himself, that he truly believes he can do no wrong," Tyler said. "But he also falls into this argument that if you admit fault that it shows weakness, and his ego can't allow him to believe that he's weak."

On the international stage, a recent Yale Management School survey found that, in Trump's stead, 75 percent of leaders in business, academia and government said they have found themselves apologizing for the president to global business partners.

Veteran Republican strategist Ron Bonjean said apologies only make sense if the contrition is real.

"Authenticity is the key to breaking through the political nonsense," Bonjean said. "Apologies delivered by elected officials are often viewed as insincere to voters because many times it's obvious that they don't really mean them."

For Trump, he said, the reluctance to apologize is a core part of his political identity.

"The appeal of Trump never giving an apology is refreshing to his base because he is seen as projecting strength and rejecting the political crisis-management formula," Bonjean said. "If politicians are truly sorry for their action, then they better mean it and then do something to make it better fast."

As is the case on any number of specific issues, and when it comes to his overall approach to governing and campaigning, Trump will have to decide over the next two years whether the potential gain of building bridges outside his base is worth disappointing his current supporters.

Digging in may have helped him win before — or at least, it didn't hurt. But Schoen said it won't be effective this time around.

"I believe it does not and will not work now," he said.