Once again the Democratic Party of Japan is in disarray. Mr. Naoto Kan, the head of the largest opposition party, has resigned over his failure to make mandatory contributions to the national pension fund. In a reversal of the leadership contest that put Mr. Kan back in the saddle in December 2002, the DPJ now appears rudderless as it gropes for a new leader.

Mr. Kan seems to have only himself to blame. As is now clear, he made two mistakes. First, he failed to pay pension premiums while he was health and welfare minister in 1996. Second, before admitting his mistake, he had sharply criticized several Cabinet ministers for skipping their respective payments. He found himself defenseless after Mr. Yasuo Fukuda resigned as chief Cabinet secretary last week for missing premium payments.

Mr. Kan's antics dismayed a public already unhappy with the flawed pension system and visibly weakened his grip on the party. What's more, the dubious deal he had struck with the ruling parties over the pension reform package rekindled smoldering intraparty rifts. For all practical purposes, the DPJ is back to square one, so to speak, as it tries to put its house in order.