The ruling Saenuri Party emerged unscathed in Wednesday's parliamentary by-elections which would restore the momentum for its reform drive and strengthen the mandate of chairman Kim Moo-sung.
The party took three of four seats up for grabs despite a high-profile corruption scandal involving top government and party officials.
The opposition New Politics Alliance for Democracy suffered crushing defeats in constituencies where political liberals had shown strong showings in past elections. It lost its stronghold of Gwangju to a defector of the party.
The ruling party was hit hard by the snowballing bribery scandal involving President Park Geun-hye's close confidants, providing a strong political weapon for the opposition party to attack just before the by-elections.
The performance is expected to not only cement Kim's leadership in the party but also raise his status as a promising candidate for next president, analysts said.
"The ruling camp now has the mandate to push the political reform of the entire spectrum, effectively overshadowing the opposition's push to use the graft scandal against the Saenuri Party," said Bae Jong-chan, senior analyst of Research and Research.
"The win is also expected to elevate the ruling party's position in future discussions with Cheong Wa Dae," he added.
Opposition leader Moon Jae-in, on the other hand, is expected to face demands to take responsibility for the defeat, the pundits said. The party is expected to face mounting calls to rethink its policy agenda and fix the internal power struggle among those loyal to former President Roh Moo-hyun and loyalists of former President Kim Dae-jung.
The by-elections were held in four constituencies ― Seoul, Incheon, Gwangju and Seongnam of Gyeonggi Province ― to pick lawmakers for the 298-member National Assembly.
The election, dubbed as "ultra mini-general election," would not have significant impact in changing the current political landscape, pundits said. But the winner of the election was expected to take a lead in the partisan fight over the escalating graft scandal and in ongoing discussions over pending issues such as pension and labour reform.
Earlier in the day, Saenuri leader Kim urged voters to pick the party's candidates, stressing that all the four constituencies need reliable support from the governing party.
"To achieve regional development, we need talented lawmakers and above all, the power of the governing party," he said during a supreme council meeting.
Opposition leader Moon, on the contrary, urged voters to give a referendum on the scandal-stricken Park administration through the by-election.
"Only votes can give an answer to the Park Geun-hye administration's failed economic policies, personnel appointment and corruption," he said at a meeting.
Analysts said the election was crucial for leaders of the rival parties, as it was their first major test.
The snowballing graft scandal involving President Park's key aides had set up a favourable environment for the main opposition party ahead of the election, said a Seoul-based political analyst Yoon Hee-woong. But the scandal failed to serve as a winning factor for NPAD in the election, he said, citing systematic limitation of the mini election.
Voter turnout stood at 36 per cent, 3.1 percentage points higher than last year's by-election.
But the slight changes in the turnout had little to do with the number of liberal voters aged between 20s and 40s ― crucial groups for the opposition party.
Yoon Pyeong-joong, political professor of Hanshin University, also played down the impact of the election, stressing that it doesn't have any of decisive factors expected to bring changes in political landscape.
"I don't think the election would become a barometer of public sentiment. The scale of the election in which parties are competing with each other for four (out of 298 parliamentary) seats is not big enough to have an impact," he said
"The election is taking place with complex feelings toward the Park (administration) conflicting together," he said.
Park continued to show her authoritative leadership through a message announced on Tuesday, Yoon pointed out.
"Park's counterattack against the opposition party could stimulate liberal voters and further disappoint swing voters who may have wanted to see her take responsibility over the burgeoning graft scandal involving her close confidants," he said. "But at the same time, her illness caused by overwork, could garner more sympathy votes from conservative voters."