The conservative ruling Saenuri Party and the liberal main opposition Democratic Party have been locked in partisan strife since President Park Geun-hye was sworn in a year ago. They have been quick to point fingers at each other over a range of controversial matters.

Last week, however, the two parties seemed less enthusiastic to take on two cases that should have been used as good occasions to criticize one another.

The opposition party backpedaled on its earlier stance on the issue of unseating a leftist lawmaker convicted of plotting an armed rebellion against the South Korean government in the event of an inter-Korean war.

Early last week, Rep. Lee Seok-ki of the minor opposition Unified Progressive Party was sentenced by a district court in Suwon to 12 years in prison. A key party official said Friday that the DP would not respond to a proposal from the ruling party to take steps to deprive Lee of his parliamentary seat until the final judgment by the Supreme Court.

This remark contradicts the position repeated by the opposition party that it “would not be too late to judge” on whether to unseat the lawmaker when a district court made a ruling.

The ruling party appeared somewhat reserved in denouncing the opposition’s flip-flopping, as its executive members decided a day earlier to allow a legislator accused of plagiarism to rejoin the party. Rep. Moon Dae-sung, a former Olympic gold medalist in taekwondo, was forced to leave the Saenuri Party in 2012 due to suspicions that much of his doctorate thesis had been plagiarized.

In reversing their positions, both of the parties seemed to have made partisan calculations ahead of the local polls to be held in June. But this short-sighted attitude will only damage their credibility among a wider bloc of rational voters. It is a pity that neither appears to realize this.