Who poses the most realistic threat to the US republic: Kim Jong Un or Donald Trump? In theory, it is obviously Mr Kim. Yet US democracy is within Mr Trump’s striking range at all times.

By providing cover to homegrown neo-Nazis, America’s commander-in-chief is giving succour to the most lethal ideology in history. The fact that the US president does not understand this — or, worse, that he knows it but does not care — is an academic question. The Ku Klux Klan and fellow travellers can scarcely believe their luck. Mr Trump is Mr Trump. The question is what the Republican party plans to do about him.

Judged at face value, the party’s leadership implicitly favours removing Mr Trump. “White supremacy is repulsive,” tweeted Paul Ryan, the Republican speaker of the House of Representatives. Mr Ryan was an implacable foe of almost everything Barack Obama proposed. Yet he never went so far as to accuse Mr Obama of backing the forces of hate. It follows, therefore, that Mr Ryan believes Mr Trump is unfit to hold the highest office in the land. So too, when privately asked, do many elected Republicans. But will they act on that judgment?