Expectations were running high for a change of power next year after the conservative main opposition People Power Party won in key mayoral by-elections in April.

Its candidates defeated rival contenders from the liberal ruling Democratic Party of Korea by a wide margin to grab the mayoralty of the country’s two largest cities -- Seoul and Busan.

In a survey conducted shortly after the elections, 55 percent of respondents said they wanted to see the next presidential vote slated for March result in a change of government. A recent poll showed the proportion had dropped to 47 percent.

On the other hand, the proportion of voters who wanted the ruling party to retain power rose from 34 percent to 39 percent.

The changing trends in voter sentiment suggest that growing public discontent with the performance of President Moon Jae-in’s government since Moon took office in 2017 cannot be seen as a guarantee of the opposition’s victory in the upcoming presidential election.

The main opposition party now seems to be embroiled in intensifying internal discord, prompting many voters to turn their backs to the party.

Lee Jun-seok, the People Power Party chairman, said last week that his party’s standard-bearer would suffer a defeat to a ruling party contender by a margin of about 5 percent if the presidential election was held now.

He should hold himself partly responsible for the diminishing prospects. He has been under criticism for failing to solidify intraparty unity and advance efforts to hold together the wider opposition bloc.

At a party convention in June, the 36-year-old Lee was elected its leader, defeating established senior politicians. He also became the youngest-ever politician to lead a mainstream party in the history of South Korea’s modern politics.

Many People Power Party members seemed to bet that a generational change in leadership would help boost the possibility of their party winning the upcoming presidential vote, though they were not confident in his ability and character.

Apparently mindful of such sentiment, Lee repeatedly said during the campaign that he would devote himself to managing the party’s presidential primaries and ensuring that it would take back power. But over the past two months, he appeared to enjoy making news headlines and focused on enhancing his personal influence rather than remain a fair manager.

He has also been at loggerheads with Yoon Seok-youl, a leading presidential contender for the party.

Lee and members of the party’s committee formed to prepare for primaries have been pushing to hold a public debate this week with more than a dozen contenders vying for the party’s presidential nomination.

But Yoon, a political novice who stepped down as the country’s top prosecutor in March, remains reluctant to participate in the envisioned debate.

Certainly, Yoon needs to be more active in holding a debate with other contenders. As his aides argue, however, it makes some sense to hold such debate sessions after the formal registration of candidates in the primaries set to kick off in late August.

The rupture of negotiations between the People Power Party and the centrist minor People’s Party on their merger does not bode well for the opposition camp’s bid for a change in government.

Announcing the no-deal end to the merger talks in Monday’s news conference, the minor party’s leader Ahn Cheol-soo avoided giving a direct answer to a reporter’s question on whether he would run in next year’s presidential election.

Ahn appeared to have decided to abort negotiations out of concern he would stand a low chance of garnering the presidential ticket of the merged party. Lee should have been more flexible in discussing Ahn’s demands regarding details of the planned merger of their parties.

It would be difficult for the opposition bloc critical of the Moon government to win in the upcoming presidential election without fielding a unified candidate.

Ahn might seek another round of negotiations with the People Power Party after the main opposition party nominates its presidential candidate in November. A possible agreement on a unified candidate could boost the chances of the wider opposition bloc in the upcoming presidential vote.

Lee and other People Power Party members should not forget that voters gave their party an overwhelming win in April’s mayoral by-elections to show their disapproval of the Moon government’s ill-conceived policies rather than simply equate it to unconditional support of the main opposition party.