The 18th South Korean presidential election was held in South Korea on 19 December 2012. It was the sixth presidential election since democratization and the establishment of the Sixth Republic, and was held under a first-past-the-post system, in which there was a single round of voting and the candidate receiving the highest number of votes was elected. Under the South Korean constitution, presidents are restricted to a single five-year term in office. The term of incumbent president Lee Myung-bak will end in 24 February 2013. According to the Korea Times, 30.7 million people voted with turnout at 75.8%. Park Geun-hye of the Saenuri party was elected the first female South Korean president with 51.6% of the vote opposed to 48.0% for her opponent Moon Jae-in. Park's share of the vote was the highest won by any candidate since the beginning of free and fair direct elections in 1987.
At the end of 2011, Park Geun-hye assumed control of the Grand National Party, which was subsequently renamed the Saenuri or New Frontier Party in February 2012. She distanced herself from Lee and led the party towards the center. In legislative elections in April 2012, Park guided the party to an upset victory, returning its majority in the National Assembly. This contributed to an increase in her poll ratings and consolidated her position as frontrunner for the Saenuri nomination.
Opposition to Saenuri is divided primarily between the Democratic United Party and independent supporters of Ahn Cheol-soo, who has emerged as a leading potential candidate despite his ostensible silence on the race. In the DUP, focus initially lay on Sohn Hak-kyu as a potential nominee, but by late 2011 Moon Jae-in, a confidant of former president Roh, had overtaken Sohn in polls. Although the DUP invited Ahn to join the party, only 2.3% of respondents to a poll on 21 April thought that Ahn was best suited to be DUP nominee. The DUP itself has been troubled by the split between pro-Roh members such as Moon Jae-in and the "Honam wing" of former president Kim Dae-jung, represented by Chung Dong-young.
Ballot numbers for party candidates were given according to the candidate's party seat distribution in the National Assembly. Ballot numbers for independent candidates were determined through a random lottery by the National Election Commission.
The 2012 Democratic United Party presidential primary saw an open primary system implemented for the first time. This new open primary introduced "mobile voting"; it was hailed as a "revolution in voting" because people could participate in voting more conveniently. However, controversies persisted during the primary elections, as questions of the legitimacy and trustworthiness of the voting results were raised.
The official result was announced on 16 September 2012, at 15:32 KST, naming Moon Jae-in the presidential candidate from the Democratic United Party. After nominated, Moon stated that he would like to join forces with Ahn Cheol-soo.
The first member of the Saenuri Party to officially announce their candidacy was Kim Moon-soo on 22 April. Kim, a former labor activist, stated in his announcement that he would focus on combating regional and socioeconomic divides, emphasized his commitment to a policy of multiculturalism, and argued for a revision in Saenuri's primary system. He stated further that Park Geun-hye's leadership of the party represented only an "ambiguously prevailing trend", and could not be relied upon to reach victory in the elections. Although Kim said that he was "convinced" he could "attract more support than [Park]", he is not widely expected to garner a high level of support. His early announcement was regarded as an attempt to preemptively form an anti-Park faction in the party.
Chung Mong-joon, a billionaire and longstanding member of the National Assembly, followed on 29 April. In his announcement, Chung emphasized the need to confront regionalism and factional politics, and stated that he would "write a new history of the Republic of Korea by facilitating [his] experience of managing a business, engaging in diplomacy and creating unity in the nation". He stressed that his task was to "bring together the divided hearts of the people" and that he was concerned that the "country could collapse in its current situation". Like Kim Moon-soo, Chung is expected to be at a disadvantage to Park. Chung previously declared his candidacy in the 2002 presidential elections but later dropped out to endorse Roh Moo-hyun.
The former Mayor of Incheon, Ahn Sang-soo, declared his candidacy on 6 May, emphasizing his economic credentials and stating that he would relieve the burden of debt. Former presidential Chief of Staff Yim Tae-hee followed on 8 May, issuing a call for Park Geun-hye to act as a "kingmaker" that was interpreted as a request for her to step aside. Yim, a moderate, proposed to join hands with independent Ahn Cheol-soo and DUP frontrunner Moon Jae-in in a bid to "demolish outdated politics". On 10 May, five-term lawmaker and former Minister for Government Legislation and Special Affairs Lee Jae-oh announced his bid, promising to reform the constitution and cut his term as president to three years.
The campaign for the Saenuri primaries has been characterized by a dispute between Park Geun-hye, as frontrunner and party leader, and her opponents in the party. She was cited in 2009 as the most influential politician in South Korea, and has outranked other candidates in many polls throughout 2012, though as of early May 2012 she is yet to officially declare her candidacy. Park's opponents have called for Saenuri to adopt an open primary system rather than the present system based on an electoral college and opinion poll results. At the end of April the Democratic United Party suggested a joint discussion on the issue of fully open primaries. Park has been criticized for her taciturn and authoritarian style in leading the party, and Kim Moon-soo described her as overly "secretive". Chung Mong-joon stated that under Park's leadership, "democracy in the party [had] gone missing". Park strengthened her position when her ally Lee Hahn-koo was elected Saenuri's floor leader on 9 May.
During a primary debate on 7 August 2012, primary candidate Kim Tae-ho asked if Park Geun-hye would agree that the May 16 coup by her father (Park Chung Hee) was both a coup and a “necessary decision,” regarding Park's previous stance that the overthrow was a “revolution to save the country”. Park confirmed her stance by answering, “I don’t think it’s the place of politicians to be fighting over whether [the May 16 incident] were a ‘coup d’etat’ or a ‘revolution’”. She furthermore commented that “no one can refute that the events themselves did happen, whether you call them a ‘coup’ or a ‘revolution.’” and that “we need to leave that issue” for history to decide. In addition, during another debate on 8 August 2012, the moderator asked Park the minimum hourly rate for a part-time worker as of 2012. Park replied “I think it’s over 5,000 won, isn’t it?,” when the legal minimum wage was 4,580 won. In response, The South Korean Confederation of Trade Unions responded with a statement in which it said, “It is terribly discouraging when a person who wants to become president does not even know the country’s minimum wage, which is a minimal right for survival and the first step toward a welfare state.”