Rival political parties seemed to mistake the April 29 by-elections, which will be held in four parliamentary constituencies, for general or presidential polls when they put forward large-scale campaign pledges this week.

The liberal main opposition New Politics Alliance for Democracy promised to create 100,000 new jobs and 600 day care centers every year as well as to provide tuition fees for high school students from working-class and middle-income families. Party policymakers claimed funds needed to implement these pledges could be raised mainly by increasing the highest rate of corporation tax by 3 percentage points.

It is no wonder that the public questions whether it makes sense to churn out such oversized programs just to win the elections to choose four legislators who will serve only until the current National Assembly finishes its four-year term in April 2016. And NPAD officials themselves may probably be unsure about the plausibility of the funding plan.

The conservative ruling Saenuri Party was barely more moderate and rational. It pledged expensive construction and housing projects in the contested districts without suggesting concrete financing schemes.

The two main parties promised massive welfare programs that went beyond the nation’s fiscal means in the general and presidential elections in 2012. They have recently blamed each other for disruptions in free child care and school meal programs.

The failure to fund these benefit schemes has caused conflicts between recipients. The central government and municipalities have also clashed over how to share the ballooning financial burden of supplying them.

The main parties should have apologized for this confusion before disclosing their lists of irresponsible pledges ahead of the upcoming by-elections.

Certainly, Korea’s welfare spending still remains at the lowest level among major advanced nations. But it is increasing at the fastest pace, with experts predicting that fiscal expenditure on benefit programs will nearly quadruple within 10 years.

Korea needs to focus on discussing how to secure the necessary funds and improve the efficiency of the overall welfare system. If it is inevitable, some benefit programs will have to be readjusted.

The leaders of the rival parties ― Rep. Kim Moo-sung of the Saenuri Party and Rep. Moon Jae-in of the NPAD ― may think that the results of the upcoming by-elections will hold the key to whether they can consolidate their status as potential contenders for the next presidential vote in 2017. If so, they need to be more rational and responsible, instead of making pledges that will prove infeasible.