When lawyer-civic activist Park Won-soon declared his candidacy for the Seoul mayoral by-election a month ago, his approval rate hovered around 5 percent. When he won the endorsement of Ahn Cheol-soo, a wildly popular social critic and software businessman, Park’s approval figure shot up close to 50 percent.

Now the sole opposition candidate for the Oct. 26 vote, after edging Democratic Party’s Rep. Park Young-sun through a complex primary procedure, the 55-year-old independent faces an important choice ― whether he should join the main opposition party.

DP membership would ensure more devoted campaigning by the party, with its organizational strength. Yet, he knows where his high popularity came from. His alliance with Ahn was based on their common stand against Korea’s inefficient and strife-torn partisan politics. Running on a party ticket is not only illogical but risks giving up votes from the many who are sick of the main parties.

After winning the primary on Monday, Park said he would make a decision after deep contemplation, considering public opinion. More than anything else, Park will now have to seek Ahn’s advice as his continued support is vital for victory against the Grand National Party candidate, Na Kyung-won, 47, an executive member of the ruling party.

Ahn returned to his chair at Seoul National University, where he is dean of the Graduate School of Convergence Science and Technology, after his brief engagement with politics over the Seoul mayoral candidacy in early September. But his strong influence over the political climate was again shown in the mayoral primary. Many now believe that the political influence of the soft-spoken ex-doctor will probably spread to the parliamentary and presidential elections next year.

Park Won-soon, launching his campaign, coined the catch phrase of “city administration for the people” to sum up his 10 major policies. They include full free lunches for primary and middle school students, the original issue that caused former Seoul Mayor Oh Se-hoon to call a city-wide referendum, which fizzled due to an insufficient voter turnout. Among others are an end to “demonstrative” construction projects initiated by Oh and turning all non-regular workers under city employment to regular status.

The GNP’s Na Kyung-won will also produce a broad set of welfare policies independent of her party’s generally conservative welfare framework in order to appeal to the lower-income voters. Yet, she will first seek to get the endorsement of Park Geun-hye on her policy items in an effort to solicit the help of the party’s presidential frontrunner, who is popular among conservative voters.

The Oct. 26 vote is a by-election to pick the capital city mayor to serve until the first half of 2014. But its significance in Korea’s political history will be immense not only because a civic activist without any party affiliation is running as favorite against a ruling party nominee for the first time. More important is that it could be a turning point to shift the pattern of Korean politics from decades of confrontation to fair competition in common pursuit for a better quality of life.

The candidates from the ruling and opposition camps need to be aware that they have to become the champions of “new politics,” as the nation has had enough of the perceived predatory politics under periodic changes of power between left and right. They should realize the true meaning of the Ahn Cheol-soo phenomenon.