The rival parties are set to begin their official election campaigns this week as unexpected challenges cloud the outlook even in their traditional strongholds.

The ruling Saenuri Party is facing a strong challenge from independent Oh Keo-don, whose campaign was merged with that of the New Politics Alliance for Democracy candidate, in Busan. The main opposition NPAD, for its part, is faced with the possibility of losing the Gwangju mayoral race to another independent candidate.

For the NPAD’s leaders, the Gwangju mayoral race will be a make-or-break election.

Since its launch, the NPAD has been plagued with internal discord stemming from the candidate nomination system, a core element of its much-touted “new politics.”

Since the party backtracked on its promise to abolish the system, a number of party members have severed ties with it, accusing the leadership of biased selection.

Two such defectors ― Lee Yong-sup and former Gwangju Mayor Kang Woon-tae ― are now threatening to break the main opposition’s hold on the city.

According to a recent survey, Kang would outpace Yoon by nearly 8 percentage points if Lee folds in his favor. Lee, with Kang’s support, is also ahead of the NPAD candidate by about 2 percentage points.

Reflecting the gravity of the situation, NPAD cochairman Rep. Ahn Cheol-soo spent the weekend, including the symbolic May 18, attempting to appease Gwangju voters. May 18 is the date of the Gwangju Democratization Movement of 1980, when a protest was suppressed with lethal force by the Chung Doo-hwan administration.

“I feel sorry for not being able to consult with Gwangju citizens,” Ahn said Saturday.

“I saw (the nomination of Yoon) as widening the choice for citizens who want Gwangju to change.”

As for the ruling party, a loss by its candidate Seo Byung-soo in Busan would be an unprecedented blow. Not only has Busan long been a conservative stronghold, but Seo is a prominent member of the pro-Park Geun-hye faction.

The Seoul mayoral race, meanwhile, appears to be leaning towards former Seoul Mayor Park Won-soon of the NPAD, with the gains made by Saenuri Party’s Chung Mong-joon being lost since the April 16 ferry disaster.

Chung’s campaign has been dealt a double blow by the ferry disaster. His party’s ratings were reduced to the lowest seen in weeks, while his youngest son chose to call Koreans’ reaction to the accident “primitive,” dealing what may be irreparable damage to Chung’s chances. According to a recent poll conducted by a local daily, Chung trails Park by 20 percentage points.

The outcome of the Incheon mayoral election appears to be as unpredictable as any, with polls showing wildly different figures for the NPAD’s Song Young-gil and former Security and Public Administration Minister Yoo Jeong-bok of the ruling party.

By Choi He-suk (cheesuk@heraldcorp.com)