When Joe Biden talks on Saturday about US democracy on the brink, there’s no doubt that it will be a campaign speech. Maybe the most important one of his life. But the speech will be more than that. It’s intended as a warning and a red alert, delivered on the anniversary of the violent January 6 insurrection at the Capitol. The date was chosen for good reason – to make the point that more mayhem and more flagrant disregard for the rule of law and fair elections, are just around the corner if Donald Trump is re-elected. Can the political...