They warn generals not to fight the last war. The same admonition might apply to presidential races. Donald Trump was out on the White House lawn attacking Joe Biden with his usual battery of epithets — ‘dummy,’ ‘loser,’ and so forth — and it sounded like déjà vu all over again. Even as he derides Biden as ‘slower than he used to be,’ it is Trump who is starting to look as though he’s losing his mojo.