The bombshell in the interview with Vice President Biden Friday on “Morning Joe” may or may not bear on the accusation against him of sexual assault, newsworthy though they may be. Nor that he’s asked the Senate to look in the National Archives for any complaint that his accuser, Tara Reade, may have filed against him. Rather it’s the fact that the ex-veep is unwilling to open up another vast trove of his files — papers held by the University of Delaware.

It’s incredible — at least to us — that such a trove is off limits to the public on the eve of a presidential election. From the day President Trump announced his campaign for president, the Democratic press and politicians have been banging the drums for Mr. Trump to release his tax returns. They are, by law, the most private kind of filing on matters of private enterprise and personal earnings. The returns, though, are, nearly four years later, still being sought in court.

Yet Mr. Biden, as he seeks the Democratic nomination for president, has gone full omerta on the basic collection of papers related to his public life. The papers, he told Msnbc’s Mika Brzezinski Friday, include “a lot of speeches I’ve made, positions I’ve taken, interviews that I did overseas with people — all of those things related to my job. And the idea that they would all be made public … while I was running for public office, they could really be taken out of context.”

Who’s he kidding? Remember, back in the ancient history of 2011, how the media demanded — and got — the release of tens of thousands of private emails of Governor Sarah Palin of Alaska. That was three years after she stood for vice president and two years after she was out of public office. The press still sought her private emails, and got them. The Times ran a whole story just about the media frenzy. It turns out Mrs. Palin’s emails were clean as a whistle.

Mr. Biden should be so lucky. It may be that the Delaware trove has, as Mr. Biden insists, no documents related to Ms. Reade. And he may know; Business Insider reported Thursday that his campaign operatives visited the archive at the University of Delaware within the past year. Ms. Reade aside, though, Mr. Biden says the archive contains documents “that existed that, for example, when I met with Putin or when I met with whomever.”

Why should Mr. Biden’s dealings with Mr. Putin be kept secret from the voters in the run-up to an election for president? There are something like 1,800 boxes of files, plus 415 gigabytes of more material. Maybe there is material at Delaware on, say, Ukraine, or Hunter Biden’s dealings with Communist China. Or the Clarence Thomas hearings, or his infamous confrontation with Prime Minister Menachem Begin at the Senate Foreign Relations Committee.

What might the papers tell us about why Mr. Biden waffled on the raid that found Osama Bin Laden? The Democrats have had their Deep State allies leaking like a sieve against, in Donald Trump, a sitting American president in active dealings with foreign leaders. On what grounds is a former vice president going to try to keep secret his papers from a long career that’s now flickering into the mists of history?