If it seems like the campaign trains of both political parties have somehow gotten derailed this year, it might well be the inevitable result of a bipartisan failure to keep the tracks intact.

Not that we haven’t had bumpy rides before, of course – but nothing quite this bad on the approach to a presidential election. And sincehow this sorry state of affairs was allowed to happen has becomethe subject of considerable soul-searchingon the part of political analysts, I thoughtit might be as good a…