JOE BIDEN has a lot of the qualities Democrats should be looking for in their presidential candidate for 2020. He is genial and expansive and his working-class origins could help him win back the support of former Democrats in places that have recently voted Republican. A recent poll in Iowa, the first state to hold a vote for presidential candidates, suggests Mr Biden is the most popular of the likeliest Democratic candidates, with a 94% approval rating among Democrat voters. A former vice-president and six-term senator, he also boasts the experience that younger Democratic leaders lack.

Aside from his age—Mr Biden will turn 78 in 2021—there is nonetheless one aspect of his experience that could scupper a presidential run. In 1991 Mr Biden was chairman of the Senate Judiciary Committee when it probed Anita Hill’s allegation of sexual harassment by her former colleague, Clarence Thomas, then a nominee for the Supreme Court. Unfortunately for Mr Biden, the offhand way that committee treated Ms Hill has been picked over since Christine Blasey Ford testified to it last week about her alleged long-ago assault by Brett Kavanaugh, President Donald Trump’s Supreme Court nominee.

Twenty-seven years later footage of the committee’s members interrogating Ms Hill makes uncomfortable viewing. The senators’ questioning was hostile and often accusatory. This time round, anxious to avoid such an impression, committee Republicans hired a female prosecutor to question Ms Blasey. Mr Biden has often said he rues the way Ms Hill was treated. “Anita Hill was vilified when she came forward by a lot of my colleagues; character assassination,” he said in an interview shortly before Ms Blasey appeared before the committee. “I wish I could’ve done more to prevent those questions and the way they asked them.”

But that slightly dodges his role in it. Mr Biden did not just oversee senator’s questioning. He bowed to Republican demands that Mr Thomas testify both before and after Ms Hill, giving the judge an advantage. Mr Biden refused to call witnesses who said they could back up Ms Hill’s testimony. He himself asked Ms Hill some questions that seemed certain to make her uncomfortable, including: “What was the most embarrassing of all the incidents you have alleged?”

In the years since, Mr Biden has emerged as something of a champion of women’s rights. He authored important legislation covering the way violent crimes against women are investigated and prosecuted, the Violence Against Women Act, passed in 1994. In 2014 he and Barack Obama launched an “It’s on Us” campaign against sexual assault on college campuses.

All that, however, is unlikely to act as much of a buffer against his role in Ms Hill’s humiliation. Her experience prompted a surge of women into political office in 1992. That “year of the woman” has been dwarfed by a much bigger one in 2018. Fuelled by anger over Mr Trump’s treatment of women and the wider #MeToo movement, a record number of women are running for office in the mid-terms in November. This new movement is likely to shape politics and especially the Democratic Party for years to come.

So what should Mr Biden do? The answer seems pretty obvious. While he has publicly regretted the behaviour of other senators on the committee in 1991 he has not yet directly apologised to Ms Hill for his own. “It’s become sort of a running joke in the household when someone rings the doorbell and we’re not expecting company,” Ms Hill told Elle magazine. “‘Oh,’ we say. ‘Is that Joe Biden coming to apologise?’ ” She added that his apology was not a priority for her. If Mr Biden does want to run in 2020—or even campaign for whoever does—it should be for him.