Joe Biden hasn’t offered a full-throated apology for his treatment of Anita Hill in the 1990s. He hasn’t backed away from his view that busing was the wrong way to integrate schools in the 1970s, nor has he denounced his decades-old positions on banning federal funding for abortion services.

Over the past few days, as several women have complained that he had made them uncomfortable by touching them in separate encounters, he has adopted a tone of defiance mixed with a smidgen of contrition. He said women have a right to their views, vowed to change his behavior in the future — but made it clear that he doesn’t believe he ever acted inappropriately.

Numerous other Democratic candidates are atoning for their past personal and political sins with effusive apologies on a host of fronts, but Biden is striking an altogether different posture. It’s a strategy employed by Bill Clinton — or, more recently, President Trump — to hold firm and refuse to apologize, preventing enemies from pouncing on any weakness. It comes with one big risk: alienating the very people upset at them and those who support them.

Trump, perhaps not the most objective observer given the numerous allegations of sexual misconduct he faces, urged Biden not to apologize when asked about the former vice president by reporters.

“I wish him luck,” he said.

Biden allies defend his refusal to apologize for actions he said were not meant to be offensive, and they point toward women who have rushed to his defense. But if he decides to enter the presidential race, Biden’s limited response will test whether Democratic voters are willing to accept a candidate who not only has held positions or done things that have fallen out of favor but has yet to fully answer for them. To make it even more complicated, Biden’s actions have touched most directly two giant Democratic constituencies, blacks and women.

Throughout his decades in public life, Biden has never been one to freely offer apologies, particularly when he is confronted with charges that cut to his character or a personal decision.

During his first presidential campaign, in 1987, he was accused of plagiarizing speeches — as well as a law review article he wrote in law school. He insisted that it was “much ado about nothing.”

“In the marketplace of ideas in the political realm, the notion that for every thought or idea you have to go back and find and attribute to someone is frankly ludicrous,” he said. A week later, he withdrew from the race.

“The exaggerated shadow” of his mistakes, he said, had “begun to obscure the essence of my candidacy and the essence of Joe Biden.”

On the day he announced his next presidential campaign, in 2007, he was besieged by criticism for calling then-Sen. Barack Obama (D-Ill.) “the first mainstream African American who is articulate and bright and clean and a nice-looking guy.”

Biden, holding a conference call with reporters, was not fully repentant.

“I really regret some have taken totally out of context my use of the word ‘clean,’ ” he said.

In 2014, the White House said that then-Vice President Biden had apologized to Turkey’s President Recep Tayyip Erdogan for suggesting his country had mistakenly helped terrorist groups. Biden insisted he had not, in fact, apologized.

“I never apologized to him,” Biden said in a CNN interview. “I know him well. I’ve dealt with him. I called him and said, ‘Look, what was reported was not accurate to what I said. Here’s what I said.’ ”

One rare apology contained an acknowledgment that he couldn’t quite wrap his head around what he was about to do. It occurred in 2013, when he visited Selma for the annual commemoration of Bloody Sunday.

“I regret and — although it’s not a part of what I’m supposed to say — I apologize it took me 48 years to get here,” Biden said before marching across the Edmund Pettus Bridge, where civil rights activists in 1965 were attacked by police. “I should have been here. It’s one of the regrets that I have and many in my generation have.”

More recently, he has tried to answer to some of the positions he has held over his nearly five decades in public life. During a Martin Luther King Jr. Day breakfast this year, he attempted to address his support for a 1994 crime bill.

“I haven’t always been right,” he said. “I know we haven’t always gotten things right, but I’ve always tried.”

Last week, he attempted to address criticism that he mishandled Hill’s testimony during the confirmation hearings for Supreme Court Justice Clarence Thomas. “To this day, I regret I couldn’t give her the kind of hearing she deserved,” Biden said. “I wish I could have done something.”

The comment triggered more criticism from those who said that he wasn’t taking ownership of his actions. He, after all, could have done something: He was the chairman of the Senate Judiciary Committee and presiding over the hearings.

“It’s become sort of a running joke in the household when someone rings the doorbell and we’re not expecting company,” Hill told Elle magazine last year. “ ‘Oh,’ we say, ‘is that Joe Biden coming to apologize?’ ”

She’s still waiting.

Biden’s advisers realized over the past few days the he needed to do more to quell the days-old controversy over his intimate style that began after Lucy Flores, the former Democratic nominee for lieutenant governor of Nevada, described Biden’s touching of her in 2014 as “blatantly inappropriate and unnerving.” Several other women have since echoed her criticism after detailing their experiences with Biden.

House Speaker Nancy Pelosi (D-Calif.) suggested that Biden’s initial comments, in which he said he would “pay attention” to the women’s complaints, had been insufficient.

“To say, ‘I’m sorry that you were offended,’ is not an apology. ‘I’m sorry I invaded your space,’ but not, ‘I’m sorry you were offended.’ Because that’s — what is that?” she asked. “That’s not accepting the fact that people think differently about communication whether it’s a handshake, a hug.”

One reason Biden has had trouble apologizing is that the criticism lands at the core of who Biden is, those close to him say. He is affectionate and, to his supporters, that is what makes him so likable.

“At least he’s engaging in a dialogue about it,” said one former staffer, “which is the most important piece.”

Politicians often struggle with apology. Mitt Romney wrote a book, “No Apology,” partly as a way to criticize Obama’s perceived willingness to apologize. Yet, this year’s crop of presidential candidates seems to have mastered it.

After harassment complaints arose regarding his 2016 presidential campaign, Sen. Bernie Sanders (I-Vt.) apologized to any woman who felt mistreated. Rep. Tulsi Gabbard (D-Hawaii) recorded a video in January to announce that she was “deeply sorry” for past anti-gay views, while Sen. Kirsten Gillibrand (D-N.Y.) apologized for her past conservative stances on immigration.

Sen. Elizabeth Warren (D-Mass.) in February apologized for her claim of a Native American ancestry: “My apology is an apology for not having been more sensitive about tribal citizenship and tribal sovereignty.”

Beto O’Rourke, the former congressman from Texas, in March apologized for not being more sensitive while talking about his wife raising their children. He also apologized for things he wrote as a teenager. He acknowledged criticism that he has enjoyed white privilege.

“Beto, or whatever his name is,” former New York mayor Michael Bloomberg said dismissively, “he apologized for being born.”

Biden so far has not offered an apology, and it’s unclear if he will.

“Biden is always going to be Biden. He’s not changing anytime soon,” said Rebecca Katz, a Democratic consultant. “Advisers around him should realize, if you’re going to be a 2020 candidate, you have to have a 2020 mind-set. But that’s not Biden. To apologize, he has to believe he did something wrong, and I don’t believe he thinks that.”