By Kiyoshi Takenaka and Linda Sieg
TOKYO (Reuters) - Former Japanese premier Morihiro Hosokawa pledged on Wednesday to push the nation to abandon nuclear power if elected governor of Tokyo next month in a race that could affect Prime Minister Shinzo Abe's energy policy and political clout.
Hosokawa, 76, backed by charismatic former prime minister Junichiro Koizumi, is billing the February 9 vote as a referendum on Abe's efforts to restart reactors taken offline after the 2011 Fukushima nuclear disaster and to make atomic energy a key power source.
"We need to turn around by 180 degrees the current energy-guzzling society dependent on nuclear power," said Hosokawa, unveiling his platform opposing reactor restarts and calling for Japan to put renewables at the core of its growth strategy.
"I foolishly once believed the myth that nuclear energy is clean and safe," he told a news conference. "That myth has completely broken down."
Abe's Liberal Democratic Party (LDP) is backing former health minister Yoichi Masuzoe, 65, who left the party after it was ousted in 2009. Abe led the LDP back to power in December 2012, pledging to revive the economy with his "Abenomics" mix of hyper-easy monetary policy, spending and structural reforms.
"This is one election the Abe government cannot afford to lose," said Nihon University professor Tomoaki Iwai. "Two losses in a row would come as a big shock to them."
Abe suffered a rare setback on Sunday when an LDP-backed candidate lost the election for the mayor of the Okinawa city of Nago to the incumbent, who opposes a government plan to move a controversial U.S. Marines' air base to his city.
Hosokawa served less than a year as premier at the head of a pro-reform coalition that ousted the LDP in 1993 for the first time in nearly four decades. He quit amid criticism over a 100-million-yen ($958,900) loan he had received 12 years earlier from the scandal-tainted Sagawa Kyubin trucking firm.
On Wednesday, he repeated that he had paid back the loan in full but apologized for the trouble caused by his resignation.
The media-savvy Koizumi, 72, was one of Japan's most popular leaders during his 2001-2006 term and was once Abe's mentor. Both supported nuclear power in office but changed their stance after the Fukushima disaster, the world's worst nuclear accident since Chernobyl in 1986.
FINANCIAL MARKETS WATCHING
Tokyo financial markets are watching the election closely. Some experts said a Hosokawa win would deal a blow to Abe's agenda. Abe's government says restarting reactors is vital to cut electricity costs and a ballooning fuel import bill.
Nuclear power made up almost 30 percent of Japan's electricity supply before Fukushima, but all the country's 48 reactors are now offline for safety checks.
"Abe's political capital will be damaged if his candidate is defeated by Koizumi," said Shusuke Yamada, chief Japan currency strategist at Merrill Lynch Japan Securities. "That could limit what Abe can do and undermine Abenomics."
Others, however, dismissed such predictions.
"His (Hosokawa's) main campaign platform is anti-nuclear power, though the office has no control over it," wrote Nicholas Smith, head of equities strategy at CLSA in Tokyo.
"Fears he threatens Abenomics are unfathomable."
Tokyo doesn't host any nuclear plants, but the metropolitan government holds a stake of 1.2 percent in Tokyo Electric Power Co Inc, operator of the wrecked Fukushima plant.
A tsunami smashed the Fukushima plant on March 11, 2011, causing meltdowns, radiation leaks and mass evacuations.
Hosokawa's candidacy could tap into a deep well of anti-nuclear sentiment, although he was vague about precisely how he planned to sway national policy. But his age and his hasty departure from office two decades ago could weigh against him.
The election follows the resignation of then-governor Naoki Inose in December - three months after Tokyo won its bid to host the 2020 Olympics - over his receipt of 50 million yen from a scandal-hit hospital chain.
"It is unclear how much destructive power Mr. Koizumi has, how upfront he will be (in supporting Hosokawa), and whether or not we have some sort of a boom," Nihon University's Iwai said.
(Additional reporting by Hideyuki Sano; Editing by Clarence Fernandez)