But is Mr. Biden a plausible alternative? He would have a far better chance to beat her than current pretenders Bernie Sanders, Martin O’Malley or Jim Webb. The Veep has long experience with the issues, has a solid base of support among unions and Democratic stalwarts, and comes across as a more authentic economic populist.

On the other hand, he’s not likely to fire up the left-wing partisans who are most frustrated with Mrs. Clinton’s machine candidacy. Mr. Biden first ran for President in 1988 and in 2008 barely registered in the primary voting. As a 72-year-old white man, he’d be running to deny Hillary her historic moment as the first woman President. In a party that is so driven by identity politics, the gender card and the minority vote are Mrs. Clinton’s biggest advantages.

All of which means that to have any chance of winning Mr. Biden would have to go after Mrs. Clinton’s greatest weakness, which is her incorrigible dishonesty. No Democratic competitor has dared to raise that issue against her, though every Democrat knows it is the pall that will hang over her general election candidacy. There isn’t much difference between Mr. Biden and Mrs. Clinton on the issues. His biggest advantage is that he lacks the Clinton ethical baggage. If he wants to beat her, he’d have to use it.