A government minister on Friday said Japan had to decide on its participation in a huge Pacific-wide free trade deal before national polls, in what could be an early salvo in the election campaign.
Tokyo has been non-committal on the US-backed Trans-Pacific Partnership (TPP) amid fierce opposition from its cosseted farming industry, although it has previously flagged an interest in joining.
Participation by the world's third largest economy would give a shot in the arm to a pact seen as a key plank of US President Barack Obama's pivot to Asia, and a counterbalance to China's rising regional clout.
A newspaper on Friday said Prime Minister Yoshihiko Noda may declare a pro-TPP hand later this month, partially as a way of putting clear blue water between his governing Democratic Party of Japan and their opponents.
"We should decide by next elections" on whether to join the TPP, Economy, Trade and Industry Minister Yukio Edano told a news conference.
His forthright cabinet colleague, State Minister for National Policy Seiji Maehara was more bullish, telling reporters Japan "should join the TPP", while chief government spokesman Osamu Fujimura said the issue could be "contested ground" in upcoming polls.
The Yomiuri Shimbun, quoting aides to the prime minister, reported Noda was mulling announcing Japan's participation later this month and then calling general elections for December or January.
Polls must be held by the end of next summer, but Noda is under pressure to go to the public earlier.
The TPP began life as a small grouping of countries around the Pacific Ocean, but gained significance when the United States joined in 2008.
It now includes Australia, Brunei, Canada, Chile, Malaysia, Mexico, New Zealand, Peru, Singapore, the US and Vietnam.
Hiromasa Yonekura, head of the Japan Business Federation "Keidanren" said Japan should join the trade forum at latest next year, calling it "the last chance".
"The year 2013 is very important for TPP," he said. "It would be almost nonsense for Japan to join the partnership if it misses this opportunity."
The issue is divisive in Japan, where domestic industries that have traditionally enjoyed high levels of protection, such as farming and pharmaceuticals, are reluctant to be exposed to global competition.
Noda may make the announcement when he meets Obama on the sidelines of this year's East Asia summit, which will be held in Cambodia from November 18 to November 20, the Yomiuri said.
He is planning to include participation in his party's pledges for an election campaign against the conservative opposition Liberal Democratic Party (LDP), the mass-circulation daily said.
The LDP is largely opposed and the issue could be a point of difference in a political landscape dominated by largely undifferentiated policy positions.
However, Noda risks incurring the ire of some members of his own DPJ, especially those representing farming communities and is seen as unable to show his cards while parliament is still sitting, for fear defections would whittle away his slim majority.