OSAKA, Japan - Barring an unexpected turnaround, Japan on Saturday will become a nuclear-free nation for the first time in more than four decades, at least temporarily.

Japan's leaders have made increasingly desperate attempts in recent months to avoid just such a scenario, trying to restart plants shut for routine maintenance and kept that way while they tried to convince a skittish public that the reactors were safe in the wake of last year's nuclear catastrophe. But the government has run up against a crippling public distrust that recently found a powerful voice in local leaders who are orchestrating a rare challenge to Tokyo's centralized power.

As the last of 50 functional commercial reactors is set to go offline Saturday, that local resistance to turning plants back on has confronted Japan's leaders with a grim scenario: with the nation's once vaunted balance of trade already deteriorating, they now face the looming prospect of summer power shortages that could drive still more factories to close or move abroad.

Halting all the reactors "would be something like a group suicide," said Yoshito Sengoku, acting chief of the governing Democratic Party's policy committee.

The showdown between local and national leaders has played out in recent weeks at a plant in Ohi, near Osaka, which the government of Prime Minister Yoshihiko Noda has set up as a crucial test case of Japan's nuclear future. Two reactors at the idled plant were the first to pass simulated stress tests meant to show that most reactors, unlike those at the Fukushima plant devastated in last year's earthquake and tsunami, could withstand similar disasters. The administration trusted that Ohi's reactors would be back in operation by now, or at least would receive local approval to start up soon.

Instead, the central government has found itself battling an improbable adversary: Osaka's mayor, Toru Hashimoto, the young, plain-speaking son of a yakuza gangster who has ridden Japan's loss of faith in government to become, seemingly overnight, the country's best liked politician, according to recent polls.

David Fuller's view From WW2 to Fukushima, Japan has more reasons to be wary of nuclear power than any other nation. Lacking fossil fuels and deriving nearly 40% of its energy from ageing nuclear reactors prior to Fukushima, Japan obviously needs this source of energy even more than most other industrialised societies.

Japan is also a well known earthquake zone. Nevertheless, the Ohi Nuclear Power Plant is on the far safer west coast of Japan, unlike Fukushima which is on the east coast and therefore exposed to the full force of a nearby Pacific tsunamis.

Modern nuclear power plants are inevitably much safer than those built in the 1960s and 1970s. As a leader in the industry, Japan has the technological knowledge to modernise and also relocate, where necessary, the nuclear power plants required for its long-term prosperity. Yet this may not happen.

We see similar reactions across Europe, despite both France's and Germany's own nuclear technology and capabilities. It is their democratic choice, as it is in Japan. However, I wonder if we are also witnessing exaggerated concerns, perhaps even irrational fears, not unrelated to economic problems in both Japan and Europe. Contrast this response with the greater optimism and nuclear programmes in growth economies, many of which are also democracies.