TOKYO (AP) — The surprise entry of a 76-year-old retired prime minister-turned-potter in the Tokyo governor's race is turning the election into a virtual referendum on the future of nuclear power in post-Fukushima Japan.

Morihiro Hosokawa, who led Japan two decades ago, has emerged as a front-runner, backed by another former prime minister, the hugely popular Junichiro Koizumi, one of Japan's longest-serving leaders.

Both are known as opponents of nuclear power, and a Hosokawa victory could deal a setback to Prime Minister Shinzo Abe's push to restart Japan's nuclear power plants and export nuclear reactors.

"I have a sense of crisis that our country's survival is at stake over various problems Japan faces, particularly nuclear power," Hosokawa said last week. He has scheduled a news conference for Wednesday to lay out his platform.

The graying Koizumi, standing next to Hosokawa at a Tokyo hotel when he first publicly endorsed him, said the Feb. 9 election is going to be a battle between those who say Japan has no future without nuclear energy and others who say Japan needs a future without nuclear energy, and can prosper without it.

When in power, both men supported nuclear power. But they have turned against it, Koizumi after the 2011 earthquake and tsunami that led to meltdowns at the Fukushima Dai-ichi power plant, and Hosokawa several years before that.

Until the veteran duo came into the picture, the poll to choose a replacement for Naoki Inose, who resigned last month over a money scandal, was seen as routine, focused on the city's preparations to host the 2020 summer Olympics.

But now the election is developing into a proxy battle between Koizumi and Abe that could divide the ruling Liberal Democratic Party over nuclear energy policy.

Abe's government is strongly pro-nuclear, and hopes to restart as many reactors as possible. All 50 of Japan's commercial reactors are currently offline. But some within his party have voiced opposition to or reluctance about nuclear power, and more are believed to be in hiding.

His Cabinet has postponed approving a new energy policy, apparently to avoid the topic until after the Tokyo election, but the draft says nuclear energy should remain a fundamental part of Japan's energy mix.

Resource-poor Japan originally turned to nuclear power decades ago to promote industrialization and economic growth and later to keep from becoming so reliant on imported fossil fuels. Before the 2011 Fukushima crisis, nuclear power generated about a third of its electricity.

Since then, Japan's public has largely turned against nuclear power. The Asahi newspaper survey in November showed 60 percent of respondents supported Koizumi's "zero nuclear" policy, compared to 25 percent who opposed.

"If Hosokawa wins, this is big trouble for Abe and his advocacy for restarting nuclear reactors," said Jeff Kingston, head of Asian Studies at Temple University in Tokyo.

The leader of Tokyo could have significant impact on national energy policy.

The city of 13 million — with millions more in surrounding suburbs — is among the world's biggest economies and is among the top shareholders of Tokyo Electric Power Co., which operates the Fukushima Dai-ichi plant and two other nuclear power plants in Fukushima and Niigata, both with anti-nuclear governors.

Even though both men have been retired for some time, Hosokawa has a good chance because of Koizumi's popularity and reputation as a principled reformer, experts say. Koizumi, 72, served as prime minister from 2001-2006.

Over their political careers, Koizumi and Hosokawa were both allies and opponents. A descendant of a warlord in southern Japan, Hosokawa became famous in 1993 as the first non-LDP prime minister to lead Japan since 1955. He resigned nine months later over a money scandal and has devoted himself to making pottery since retiring from politics in 1998.

Some experts say that over time, a victory by Hosokawa — with crucial backing from Koizumi, a one-time LDP stalwart — might bring more voters to support the ruling party. The anti-nuclear agenda promoted by Koizumi could become a new mainstream and attract a broad range of voters who are otherwise uninterested or consider anti-nuclear as a thing of the radical left, they say.

"Koizumi will rake in voters out there while traditionally anti-nuclear, liberal-leaning parties have failed to gain support even after the Fukushima accident," said Koichi Nakano, a political science professor at Sophia University in Tokyo.

The pair's presence has already prompted other candidates to add anti-nuclear agenda to their platform.

All but one of four main candidates now say they support nuclear phase-out, including former Health Minister Yoichi Masuzoe, who is backed by the ruling party. Even Abe has promised to reduce dependency on nuclear energy, but says a total phase-out is unrealistic.

The prime minister is clearly taking note. Abe cautioned during his tour of Africa that the Tokyo governor election should focus on 2020 Olympics, social welfare and other issues, not just nuclear energy — a rare comment by a prime minister over a gubernatorial election.