The liberal ruling Democratic Party of Korea elected its new chairman Sunday following the choice of its new floor leader two weeks earlier.

The conservative main opposition People Power Party, which picked its new floor leader last week, is scheduled to hold a party convention in June to elect its new head.

The changes in the leadership of the rival parties come in the aftermath of the April 7 mayoral by-elections in the nation’s two largest cities -- Seoul and Busan. Ruling party candidates suffered crushing defeats to contenders from the main opposition party in the elections seen as a barometer of voter sentiment in the run-up to the next presidential vote less than a year from now.

The electoral outcomes revealed the depth of people’s discontent with a string of policy failures of President Moon Jae-in’s government over the years since it launched in May 2017. Various scandals involving close associates with Moon have exacerbated public anger.

Both of the two major parties have pledged to reform themselves and put forward a coherent set of measures to shore up the livelihoods of people, reinvigorate the economy and put under control the prolonged pandemic crisis.

The ruling party, which commands 174 of the 300 parliamentary seats, is facing an urgent need to regain public confidence.

The rout in last month’s mayoral by-elections shattered its streak of four consecutive electoral triumphs. It won an overwhelming victory in the parliamentary elections in 2016 and 2020, the local polls held nationwide in 2018 and the presidential vote in 2017.

Voter support for the ruling party fell 2.9 percentage points from a week earlier to 27.8 percent, the lowest since the launch of the Moon administration, according to a survey released Sunday by Realmeter, a local pollster. President Moon’s approval rating also slipped 0.8 percentage point over the cited period to a record low of 33 percent, with 62.6 percent disapproving of the way he handled state affairs.

The main opposition party is in no position to bask in the declining public support for the ruling bloc. Its victory in the mayoral by-elections was seen by political observers largely as a result of reflexive interest from voters’ disappointment with the performance of the Moon government rather than their anticipation that the opposition party would do better.

The rival parties should now compete to appeal to a growing portion of independent voters, who are key to the outcome of the upcoming presidential election.

According to a compilation of weekly polls conducted by Gallup Korea in April, 33 percent of voters placed themselves in the center of the ideological spectrum, with those who viewed themselves as conservatives or liberals accounting for the same proportion of 26 percent. A year earlier, 33 percent regarded themselves as liberal, followed by 26 percent in the center ground and 25 percent with conservative inclination.

It is particularly notable that the proportion of liberal-minded voters dropped most sharply over the past year among young people in their 20s, from 35 percent to 25 percent.

The rival parties need to change further to draw more voters in the center ground into their folds in the lead-up to the presidential election slated for March. But the leadership reshuffle in both parties have so far fallen short of public expectations.

Rep. Song Young-gil, the new head of the ruling party, has pledged to redress misplaced policies implemented under the Moon administration. It has yet to be seen whether he will be determined enough to overcome resistance from the pro-Moon faction and push through his agenda for changes. The party’s new floor leader, Rep. Yun Ho-jung, comes from the group loyal to Moon.

More fundamentally, in the eyes of many people, Song, a five-term legislator and former mayor of Incheon, is seen as yet another figure from the outmoded political establishment.

The People Power Party’s new floor leader, Rep. Kim Gi-hyeon, who serves his fourth term as legislator, faces doubts about his ability to put behind a long-standing intraparty discord over the 2017 impeachment of former conservative President Park Geun-hye.

The opposition party may send a clear signal of changes by electing a truly reformist figure, possibly from the group of first-term lawmakers, as its new chairman. Such a choice could also bring changes to the political circle as a whole and help steer the presidential race in the direction of meeting voter expectations.