Looming election may be nail in coffin for Japan's fiscal reform

* PM Abe sticks to fiscal target but ditches deadline

* Delay in fiscal target opens room for more spending

* Fledging new party calls for freeze in sales tax hike

* BOJ blamed for lax fiscal policy

By Leika Kihara and Tetsushi Kajimoto

TOKYO, Sept 29 (Reuters) - Even as a new party under a populist female leader scrambles the outlook for Japan's general election next month, one thing is clear: the winner will loosen a grip on the government's runaway debt as lawmakers forego higher taxes or boost spending.

Prime Minister Shinzo Abe wants to use the revenue from a planned sales-tax hike not to pay down debt but to spend more on education and other popular programmers.

Tokyo Governor Yuriko Koike, whose "Party of Hope" is challenging Abe's ruling coalition by effectively absorbing Japan's largest opposition party, wants to put off the tax hike altogether.

"Japan has yet to emerge from deflation as consumption, which makes up a large portion of the economy, remains weak," she told a briefing on Thursday, criticising Abe for doing little to prop up household income.

The debate is shifting to how much more to spend and in what areas, rather than on what is acceptable within the limits set by Japan's public debt, which at well over twice the size of its economy is the biggest among industrialised nations.

"Regardless of who wins, there will be increased spending because that's how you win votes," said Koichi Haji, chief economist at NLI Research Institute.

"Very few lawmakers call for fiscal reform," Haji added. "That may be fine now, but there's no telling when loss of market trust in Japan's finances could trigger a spike in bond yields." Japan's ballooning public debt has not bothered the bond market much so far, as investors trust the country can repay public debt with its huge current account surplus and abundant domestic savings.

But the long-term risk is that snowballing social security spending for a fast-ageing population will strain government finances, making it more vulnerable to a sudden spike in borrowing costs that would hurt the economy.

Japanese government bond (JGB) prices tumbled on Thursday, with the benchmark futures posting their biggest fall in three months, as investors braced for bigger spending.

WHITHER THE THREE ARROWS?

Abe came into office in 2012 vowing to eradicate two decades of economic stagnation with "Abenomics" -- his three policy arrows of fiscal spending, monetary stimulus and structural reforms. While the fiscal and monetary support reflated the economy, critics say Abe has made little progress on structural reforms.