Voters in Seoul decide on Wednesday whether all children should receive free school lunches -- a seemingly parochial issue that has drawn televised political tears and could influence 2012 elections.

The referendum was called by Mayor Oh Se-Hoon, of the ruling Grand National Party, after the opposition-controlled city council gave all grade one to six pupils free meals, instead of limiting them to those from below the poverty line.

At a live television press conference on Sunday, Oh knelt down before the cameras and began crying, appealing to voters to come out and deliver their judgment against what he branded "welfare populism".

The question has drawn in national-level politicians and the poll is being closely watched ahead of parliamentary elections next April and a presidential vote in December 2012.

The liberal opposition Democratic Party (DP) has campaigned for a referendum boycott, accusing the mayor of squandering taxpayers' money on the city's beautification projects while penny-pinching on lunch for children.

"We've seen many children crying for meals, but we've never seen an adult crying against giving meals to children," Park Jie-Won, a senior DP lawmaker, told journalists, in a jibe against Oh.

Providing students of a single year with free lunches costs an estimated 34 billion won (US$31 million) annually.

Oh, who has the backing of President Lee Myung-Bak, says a free-for-all lunch program will increase the demand for more pork barrel policies, straining an already-stretched budget.

The mayor has vowed to step down if the turnout fails to reach a quorum of one-third of the city's 8.4 million eligible voters, or if the result backs free lunches for all children regardless of income.

Expectations are that the turnout will be below the quorum in light of the mayor's low popularity and voter indifference, dealing a blow to the GNP ahead of next year's elections.

Support for the ruling party and President Lee has been eroded greatly by widening income gaps between the rich and poor, high unemployment and many undelivered election promises.

"The vote has come to be seen as a test of voter sentiment ahead of general and presidential elections next year," Choi Jin, President of the private Institute of Presidential Leadership, told AFP.

"Oh turned the otherwise plain referendum on free lunch into an all-out war between rival parties," he said.