When Texas and Ohio vote in tomorrow's Democratic primaries, they may bring Hillary Clinton's campaign for the presidency to an end. If she loses either of those states, her bid is over barring the formalities. This is a position few expected her to be in. Not long ago, success in the primaries and victory in the general election were regarded as almost inevitable. What went wrong?

For the answer, one should turn (as always) to the teachings of Marx. "The secret of success in life is sincerity," Groucho once famously observed. "If you can fake that, you've got it made."