By Jack Kim
SEOUL (Reuters) - South Korean voters in 15 districts chose lawmakers on Wednesday in by-elections that could determine whether President Park Geun-hye's ruling party can retain a majority to push through her economic stimulus policy and regulatory reform.
Park has made boosting the economy a priority in her second year of a single term and recently appointed a finance minister who has pledged to stimulate consumption and ease restrictions on the sagging property market.
Voting was taking place in the lingering shadow of the sinking of a ferry in April that killed 304 people, mostly children on a class trip. It was the country's worst maritime disaster in 44 years and the government has come under fierce criticism for what was seen as an inadequate and slow response.
Polling stations remain open until 1100 GMT, with no clear results expected for several hours after that.
At stake is control of the 300-seat parliament.
The ruling conservative Saenuri Party now holds 147 of 285 seats and a victory in four of the districts would ensure it hangs on to a majority.
Winning half the seats would pad that majority and add momentum to government efforts to proceed with reforms. Much of the programme requires no parliamentary approval, though changes to regulatory procedures must pass through a vote.
Commentators say the ruling party is likely to avoid any large-scale defeat against a weak opposition that has been unable to capitalise on the scandal surrounding the ferry disaster.
Voting was underway in six constituencies in the capital region and three in the battleground central region. Most of the seats were vacated when lawmakers quit to run for mayoral and gubernatorial elections in June or had their posts taken away for convictions on parliament election irregularities.
The general election was in 2012 and MPs serve four years.
Park has called for all-out efforts to boost the economy and Finance Minister Choi Kyung-hwan has promised billions of dollars in stimulus spending and steps to shore up demand in the property market.
Private consumption generates about half of gross domestic product, but the economy still relies heavily on exporters as their performance has a strong influence on jobs and investment.
The Sewol ferry sank on a routine trip south from the port of Incheon to the holiday island of Jeju on April 16.
The vessel was overloaded and travelling too quickly on a turn and many crew members abandoned ship as the children waited in their cabins as instructed. The coast guard was slow to respond as the ferry sank.
The disaster prompted mass cancellations of tour contracts, hurt tourism-focused businesses and crimped consumer sentiment.
Park's popularity plunged from a support rating of 63 percent to 45 percent in a poll conducted last week. Saenuri has also suffered, but has higher ratings than the main opposition New Political Alliance for Democracy.
(Editing by Ron Popeski)