Kwan Weng Kin, Japan Correspondent

Hidden agenda behind Abe's electoral gambit?

Is it really about the economy?

What does Prime Minister Shinzo Abe really hope to achieve by calling a snap general election that is expected to give him another four years in power until December 2018?

He says tomorrow's elections are about seeking a fresh mandate for his Abenomics growth policy - a combination of loose monetary policy, government spending and structural reforms.

It is the only way, he claims, to ensure that Japan can finally emerge from 15 years of deflation.

But his track record since coming to power a second time in December 2012 suggests that his topmost priority has never quite been changing the Japanese economy.

Only this can explain why his Abenomics' "third arrow" of structural reforms, the most important and complex of the policy's three components, still remains in his quiver and that the reforms he has promised still mostly have not taken off. For instance, his much-touted proposal to empower women and make them "shine" in the Japanese economy, with a 30 per cent target of women in managerial positions, has, so far, been just a lot of talk.

It has been two years since Mr Abe took power, but Japan remains seriously short of childcare facilities, which is stopping many young mothers from going back to work after having children.

What really occupied Mr Abe during these two years was the bid to broaden the interpretation of Japan's Peace Constitution so as to give the Self Defence Force (SDF) - Japan's de facto military - the right to engage in collective self-defence.

This would allow Japan to go to the aid of another country that comes under armed attack. It effectively takes Japan closer towards military normalisation.

Afraid that the opposition would try to jam debate in Parliament on such a major change to post-war defence policy, Mr Abe chose to discuss it with only his party's coalition partner Komeito before making it government policy through just a Cabinet decision in July.

All that remains now is for him to amend the necessary laws governing the SDF so he can implement the decision.

But Mr Abe is not content at merely revising the interpretation of the Constitution. He wants to revise the very Constitution itself.

In his first stint as prime minister, from September 2006 to September 2007, he tried to convince the Japanese that he was out to create a "beautiful country, Japan".

His real agenda was revealed in a January 2007 speech in Parliament that ended thus: "Towards the creation of a new country, we should deepen our discussions regarding the revision of the Constitution, which sets forth the profile and shape of our nation."

He wants to amend the war-renouncing Constitution to give the SDF a pro-active military role without the constraints of the United States-imposed war-renouncing clause.

The current Constitution was drawn up by US officials during the post-war Allied Occupation of Japan and promulgated in May 1947. After Japan recovered its sovereignty in 1952, conservatives and nationalists tried to revise the Constitution to make it more "Japanese", but were thwarted by the extreme difficulty of doing so.

Under Article 96, amendments require the approval of two-thirds of both Houses of Parliament before a national referendum can be launched for the people to vote on any proposed constitutional revision.

Such a high barrier was made more difficult by the fact that opposition parties in the past frequently controlled over one-third of the seats and that they firmly supported the status quo.

Mr Abe sees the possibility of his Liberal Democratic Party (LDP) controlling over two-thirds of the seats in the Lower House if elections are held now.

Media surveys suggest that the LDP is capable of taking more than 300 seats, and maybe even a two-thirds majority on its own.

A two-thirds majority requires a minimum of 317 seats.

The LDP held 294 seats before Parliament was dissolved last month, 325 if the seats of coalition partner Komeito are included.

The LDP argues that the present two-thirds majority requirement for both Houses of Parliament is not only too restrictive, but also anomalous, as only a simple majority in a referendum is needed to approve an amendment. Getting a two-thirds majority in the Lower House is, therefore, a crucial first step for Mr Abe.

In the Upper House, the LDP-Komeito coalition currently controls less than two-thirds of the Chamber, but may be able to secure the cooperation of like-minded opposition parties to make up the difference.

Mr Abe is said to be targeting a national referendum in mid-2016.

The first thing he wants to do will no doubt be to relax the conditions in Article 96.