In the biggest gamble of his political career, Japan’s prime minister has called an early election. Junichiro Koizumi wants a new mandate for reform.In a bid to get it, he dissolved the lower house of parliament, although it is events in the upper house that triggered his decision. It has rejected the premier’s plans to privatise the post office. The defeat came after rebels in the ruling party voted against his proposals. Now the prime minister wants to let the public decide. “I would like to ask the people whether they are for or against these postal reforms,” he said, after announcing the snap ballot. Koizumi is hoping it will see a purge of anti-reformers within his Liberal Democratic party, giving him the freedom to forge ahead with change. He has staked his reputation on reforming Japan’s post office, in moves that would transform it into the world’s biggest bank. September 11 has been named as the date for the election. Analysts say it is by no means sure to return the premier to power.