So all that really remains for her would-be challengers is to attack her ethics. There, at last, the anti-Hillary argument becomes an easy one: From the Nixonian style of her State Department operation to the way her family fattened itself on global tribute during her recent public service, her rivals can point to sins and misdemeanors that would have already disqualified a lesser candidate.

But will many Democrats really want to hear that argument? The advantage of making an ideological case against Hillary is that progressives can accept it – yes, she’s not as liberal as we would like, we’re glad somebody’s pressing her, and maybe we’ll cast a protest vote for them – and still feel O.K. about her inevitability and about voting for her in the general election.

The ethical case, on the other hand, is more personal, discomfiting, and easily repurposed by Republicans. So any time Hillary’s rivals offer those kinds of critiques, their audience will hear intimations of G.O.P. attacks to come. And since she’s almost certainly going to be the nominee, Democratic voters may not be particularly grateful for the foretaste; they may, instead, dismiss the men offering it for giving aid and comfort to the enemy.

In which case those men will still deserve our gratitude. Because then, at least, whatever happens in a Clinton presidency, her supporters won’t be able to say that they weren’t warned.