Britain's elections are just a week away, and psephologists and bookmakers agree: It's an unpredictable mess, with the most likely outcome a minority Labour government backed by Scottish nationalists. For this state of affairs, the ruling Conservative Party has itself to blame.

By any measure, Prime Minister David Cameron should be well ahead. He has a strong economic story to tell; in Labour leader Ed Miliband, he has an opponent most Brits can't picture as their leader and on Thursday night was savaged by a television studio audience that distrusted him on the economy. Tory donors accuse Cameron of running a lackluster campaign — to which he shoots back that he's "bloody lively." But the root problem is different.

If Cameron is ousted on May 7, it will be because he paid too much attention to his party's Europe-obsessed backbenchers for the past two years, instead of trying to change Conservatives' image as a "nasty party," ruled for and by the nation's monied elites.