The splitting of the strife-torn United Progressive Party has begun as the party’s reform-minded faction expelled four proportional representatives Friday so that they could retain their parliamentary seats and join a soon-to-be created new progressive party.

Under the law, a lawmaker elected through the proportional representation system loses his seat if he voluntarily quits his party. However, he can maintain his lawmaker status if the party expels him.

The four expelled lawmakers all belong to the reformist group, which accounts for seven of the party’s 13 parliamentarians. The group’s three other lawmakers, who are all district representatives, are expected to defect from the UPP soon to launch the planned party.

If the reformists all leave the party, the UPP will be left to the pro-North Korea faction, dubbed National Liberation. Then it will cease to be a progressive party as the faction follows North Korea’s anachronistic “juche” or self-reliance ideology.

The NL faction triggered the breakup of the party by refusing to oust another two proportional representatives ― Reps. Lee Seok-ki and Kim Jae-yeon ― who were found to have won their seats through a rigged primary in the April parliamentary election.

The faction denigrated the party’s reputation by wielding violence against party leaders who sought to strip the two NL lawmakers of their party membership.

The faction’s lawmakers further estranged the party from the electorate by making nonsensical comments in favor of North Korea.

Frustrated by the NL group’s undemocratic nature and total disconnect from reality, the party’s members and supporters began to turn their backs on it. Last month, for instance, the Korea Confederation of Trade Unions, the nation’s largest labor group, withdrew its support for the UPP, undermining the foundation of progressive politics in Korea.

Under these circumstances, the reformist group has no choice but to break away from the party and form a new one. Reformists face huge challenges. In the first place, they need to reenergize the progressive movement, which is in disarray in the wake of months-long factional feuds within the UPP.

For this, they should first focus on regaining support from labor groups, especially the KCTU. At the same time, they need to present a new vision for Korean society that can resonate with a large swathe of the electorate.

To highlight their separation with the UPP, reformists might include in the new party’s platform an unequivocal opposition to North Korea’s nuclear weapons program and human rights violations.

More than anything else, the new party’s leaders and rank-and-file members should practice democracy themselves. To regain support from voters, they should think and behave in a way that fits with the high democratic standards of Korean society.