[EAI Opinion Review] Factors of the Gap in Expandability Between Moon and Ahn, and Changes in the Reverse Voting Tendency of Saenuri Party Supporters

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On November 6th, a joint agreement of seven articles was announced by candidates Moon Jae-in and Ahn Cheol-soo. Discussions on candidate unification are set to begin in earnest. Therefore, this report aims to summarize the changes in public opinion and the key issues related to unification up to the point of the unification announcement. Chapter 1 analyzes the types of voters exhibiting a gap in expandability between Moon and Ahn, which has not been empirically addressed before. Chapter 2 analyzes the reverse voting tendency of Saenuri Party supporters in preference for a unified candidate, a hypothesis that has only been raised, through an operational definition of "potential strategic voters." The [Appendix] includes, as reference material, the section on candidate unification from [EAI Public Opinion Briefing] No. 124, which summarizes public opinion changes related to candidate unification up to the survey on October 27th, and the tables from [EAI Opinion Review].

1. Factors of the Expandability Gap Between Candidates Moon Jae-in and Ahn Cheol-soo in Unification

1) Comparison of Expandability and Voter Defection Rate: Lower Defection Rate When Unifying Under Ahn

If unified with Ahn Cheol-soo, 86.6% of Moon supporters would support Ahn Cheol-soo in a Park vs. Moon confrontation.

If unified with Moon Jae-in, 79.5% of Ahn supporters would support Moon Jae-in in a Park vs. Ahn confrontation.

When cross-analyzing preferences in a 1:1 hypothetical match-up with Moon Jae-in as the unified candidate (Hypothetical Match-up 1) versus a 1:1 hypothetical match-up with Ahn Cheol-soo as the unified candidate (Hypothetical Match-up 2), the responses can be categorized into a total of nine types. For Park Geun-hye's supporters, in a confrontation with Moon Jae-in, 81.7% of the 350 respondents who supported Park Geun-hye in the Park vs. Moon match-up maintained their support for Park Geun-hye (①), while 19.3% shifted their support to Ahn Cheol-soo (②, 15.7%) or others (③, 2.6%). Conversely, in a hypothetical match-up between Park Geun-hye and Ahn Cheol-soo, 85.1% of the 336 respondents who supported Park Geun-hye maintained their support for Park Geun-hye in a 1:1 confrontation with Moon Jae-in (①), with only 14.9% shifting to support Moon Jae-in (④, 11.3%) or others (⑦, 3.6%). This indicates that a confrontation with Moon Jae-in is more advantageous than a confrontation with Ahn Cheol-soo.

From the perspective of opposition party candidates, in a hypothetical Park vs. Moon match-up, out of 381 Moon Jae-in supporters, 86.6% supported Ahn Cheol-soo in the Park vs. Ahn match-up (⑤), while 10.0% supported Park Geun-hye (④) and 3.4% defected to others (⑥). Conversely, out of 415 Ahn Cheol-soo supporters in the hypothetical Park vs. Ahn match-up, only 79.5% supported Moon Jae-in in the Park vs. Moon match-up (④), with 20.5% defecting to Park Geun-hye (②, 13.3%) or other responses (⑧, 7.2%).

Although Ahn Cheol-soo's support has somewhat slowed recently in terms of overall approval ratings and preference for a unified candidate, the proportion of Moon Jae-in's supporters absorbed by Ahn Cheol-soo when Ahn Cheol-soo unifies is higher than the proportion of Ahn Cheol-soo's supporters absorbed by Moon Jae-in when Moon Jae-in unifies. This implies that a significant portion of Ahn Cheol-soo's supporters do not shift to supporting Moon Jae-in when unification occurs.

[Table 1] Cross-tabulation of Hypothetical Park vs. Moon and Park vs. Ahn Match-ups

Source: EAI · Hankook Research Regular Public Opinion Barometer Survey

2) Ahn Cheol-soo's Expansion Effect: Pro-Ahn, Anti-Moon Responders > Pro-Moon, Anti-Ahn Responders

4.3%p gain in a match-up against Park Geun-hye when unified with Ahn Cheol-soo.

-Pro-Ahn, Anti-Moon Responders: 10.6%, Pro-Moon, Anti-Ahn Responders: 6.3%

Simplifying the above table and cross-tabulating by support for Ahn Cheol-soo and Moon Jae-in in each 1:1 hypothetical match-up yields four attitude types ([Table 5]). In the Park vs. Ahn match-up, Park supporters and others are grouped as non-Ahn supporters. In the Park vs. Moon match-up, Park supporters and others are grouped as non-Moon supporters. Type ① represents non-Moon/non-Ahn supporters, accounting for 41.8% of all voters. Conversely, Type ④ represents simultaneous supporters, backing Ahn in the Park vs. Ahn match-up and Moon in the Park vs. Moon match-up. This implies that 41.2% of voters will support either opposition candidate regardless of who it is.

Type ②, Pro-Ahn/Anti-Moon supporters, consists of defectors who would vote for Ahn Cheol-soo in a unified match-up but would shift to Park Geun-hye or others in a Moon Jae-in match-up, totaling 10.6% of all voters. Conversely, Type ③, Pro-Moon/Anti-Ahn supporters, comprises those who would support Moon Jae-in in a unified match-up but would defect if Ahn Cheol-soo were the unified candidate, amounting to only 6.3%. Consequently, a unified Ahn Cheol-soo could garner support from Type ② (10.6%) and Type ④ (41.2%), totaling 51.8%. In contrast, a unified Moon Jae-in could secure support from Type ③ (6.3%) and Type ④ (41.2%), totaling 47.5%. This indicates a potential expansion effect of 4.3 percentage points for Ahn Cheol-soo when unified.

[Table 2] Classification of Support Tendencies Based on Support for Ahn Cheol-soo/Moon Jae-in in 1:1 Match-ups

Source: EAI · Hankook Research Regular Public Opinion Barometer Survey

3) Factor of Difference: Pro-Ahn, Anti-Moon Type by Demographic Group

Moon Supporter/Ahn Non-Supporter Type > Ahn Supporter/Moon Non-Supporter Type: Democratic Party Supporters - 40s

Moon Supporter/Ahn Non-Supporter Type < Ahn Supporter/Moon Non-Supporter Type: Undecided/Centrist, 20s-30s, Honam Region

In Table 6, when classifying single candidate support types by party affiliation, ideological tendency, generation, and region, the Moon Jae-in supporter/Ahn Cheol-soo non-supporter type was high only among Democratic Party supporters and those in their 40s; in all other demographics, the Ahn Cheol-soo supporter/Moon Jae-in non-supporter type was high. Particularly among undecided voters, who are important for expanding support, the Moon supporter/Ahn non-supporter type was only 5.4%, while the Ahn supporter/Moon non-supporter type was 23.9%, indicating a preference for Ahn and a problem with Moon's expandability among undecided voters. Among ideological centrists, the Moon supporter/Ahn non-supporter type was 7.2%, while the Ahn supporter/Moon non-supporter type was more than double at 14.7%. Regionally, the difference between the two types was smallest in the Chungcheong region, and the Ahn supporter/Moon non-supporter type was high in Honam at 18.5%.

For candidate Ahn Cheol-soo, maintaining the current preference structure for single candidate support is crucial. For candidate Moon Jae-in, to strengthen his competitiveness as a single candidate, maintaining a relative advantage among centrist/undecided voters is essential. Conversely, for candidate Moon, it is an urgent task for victory in unification to convert the relatively high negative sentiment among centrists/undecided voters and in the Honam region, characterized by Ahn supporter/Moon non-supporter tendencies, into favorable sentiment.

[Table 3] Classification of Single Candidate Support Types by Party Affiliation, Ideological Tendency, Generation, and Region

2. Strategic Voting Tendencies of Saenuri Party Supporters Change

1) Defining Saenuri Party's Potential Strategic Voters

In cases of candidate unification or preference surveys for single candidates, Saenuri Party supporters or Park Geun-hye supporters, who would have to compete with the single candidate, should be excluded from the analysis. This is based on the possibility of strategic voting. How many strategic voters (reverse selection) are there among Saenuri Party supporters?

Here, we define strategic voting among Saenuri Party supporters as the phenomenon of not supporting a single candidate who is perceived as a threat to their own party's candidate (the candidate among Moon and Ahn with a higher likelihood of winning). (Of course, there may be other reasons, such as supporting a candidate with a lower likelihood of winning due to personal appeal or party affiliation. Strictly defined, this may not be called strategic voting. However, since the purpose here is to estimate the general distribution and trend rather than the precise scale of strategic voting, we will adopt a loose definition.) Therefore, actual strategic voters are inclusively termed 'potential strategic voters.' In the September and October surveys conducted by the East Asia Institute and Hankook Research, respondents were asked who they believed had a higher likelihood of winning between Moon and Ahn, and their preference for a single candidate was evaluated.

2) September Reverse Selection Tendency: Increased proportion of Moon Jae-in selection due to concern over Ahn Cheol-soo's competitiveness

First, in the September survey, among Saenuri Party supporters, the proportion who responded that Ahn Cheol-soo had a higher likelihood of winning was 44.1% (120 people), while those who responded that Moon Jae-in had a higher likelihood of winning was 29.2% (96 people), indicating a perception of higher winning potential for Ahn Cheol-soo. However, even among Saenuri Party supporters who perceived Ahn Cheol-soo as having a higher likelihood of winning, the potential strategic voters who strategically switched to supporting Moon Jae-in accounted for approximately 18.3%, while 60.0% supported Ahn Cheol-soo as the single candidate with a higher likelihood of winning. In contrast, among Saenuri Party supporters (96 people) who believed Moon Jae-in had a higher likelihood of winning, non-strategic selection favoring Moon Jae-in was 81.3%, and potential strategic voters who preferred Ahn Cheol-soo, despite his lower perceived likelihood of winning, were only 6.3%.

Despite the loose definition used in this report, it can be seen that the perception of the entire Saenuri Party engaging in strategic reverse selection is significantly exaggerated. In September, the tendency to reverse-select Moon Jae-in over Ahn Cheol-soo was relatively strong, mainly due to a comparatively higher level of caution towards Ahn Cheol-soo. The fact that 56.7% of Saenuri Party supporters who neutrally assessed the winning chances of both candidates preferred Moon Jae-in indicates a stronger tendency within the Saenuri Party to relatively prefer Moon Jae-in, beyond strategic reverse selection. Among these individuals, preference for Ahn Cheol-soo was only 16.4%.

[Table 4] Evaluation of Opposition Candidate Winning Potential and Single Candidate Preference among Saenuri Party Supporters in September

* Potential strategic voters are indicated in bold.

Source: EAI · Korea Research Regular Public Opinion Barometer Survey

3) October Survey: Moon Jae-in's Reverse Selection and Ahn Cheol-soo's Reverse Selection Offset Each Other

However, in the October survey, significant changes are observed in the perception of winning potential for both Ahn Cheol-soo and Moon Jae-in, with the figures becoming comparable at 29.9% (100 people) and 30.2% (101 people), respectively. Examining the changes in the scale of strategic voting within the Saenuri Party, among those who viewed Ahn Cheol-soo as having a higher likelihood of winning, 17.0% emerged as potential reverse voters supporting Moon Jae-in, showing little change from September. Conversely, among those who responded that Moon Jae-in had a higher likelihood of winning, while 81.3% continued to support Moon in the September survey, only 68.3% supported Moon in the October survey. Instead, 13.9% identified themselves as potential strategic voters supporting Ahn Cheol-soo, more than double the previous month.

Among the 92 respondents who considered the winning potential of both candidates to be similar, 30.4% preferred Ahn Cheol-soo this month, while Moon Jae-in's preference decreased slightly to 56.7%. This suggests that the overall rise in Moon Jae-in's support, coinciding with a decline in his support among Saenuri Party supporters, can be inferred as a result of partially applied strategic choices.

[Table 5] Evaluation of Opposition Candidate Winning Potential and Single Candidate Preference among Saenuri Party Supporters in October

* Potential strategic voters are indicated in bold.

Data Source: EAI · Hankook Research Regular Public Opinion Barometer Survey

(Continued)