One Constituency, Two Parties: Ballot Splitting and Divided Loyalties in Thailand’s Election

An oft-used voter turnout slogan in Thailand encourages citizens to “vote for the candidate you love and the party you like.” Yet, the May 2023 general election unveiled a fascinating reality: the candidate Thai voters loved and the party they liked were not always aligned. This divergence reflects the varying strength of partisan attachments among the electorate, the uneven influence wielded by individual candidates, and the emergence of divided loyalties that enable political dynasties to persist, yet leave their future uncertain.

The two-ballot system was first introduced to Thailand with the 1997 Constitution. On the first ballot, voters cast their votes to elect constituency MPs using the first-past-the-post method. On the second ballot, voters select political parties rather than individual candidates. This vote allocates party-list MPs proportionally to parties based on their share of votes at the national level.

The 2017 Constitution had reverted to a one-ballot system, but a two-ballot system was reintroduced through a constitutional amendment in 2021. The two-ballot system provides voters with greater flexibility and choice in expressing their preferences, for example, enabling them to choose a candidate from one party based on local considerations, such as the candidate’s track record, or personal ties to their constituency, while simultaneously voting for another party on the party-list ballot that aligns with their broader ideological or policy preferences.

Assuming no big differences in voting errors or invalid votes in one tier over the other, the data below (Table 1) reveals that many Thai voters chose different options across the constituency and party-list ballots, leading to a discrepancy in the number of votes received by each party in both tiers.

The pattern from the recent elections is evident: Move Forward (MFP), Pheu Thai, and United Thai Nation (UTN) obtained higher party-list vote shares compared to their constituency vote shares (Table 1), indicating that voters split their votes in ways that favoured these parties on the party-list ballot. The reverse was true for other parties such as Palang Pracharath (PPRP) and Bhumjaithai (BJT). Their party-list vote shares were notably smaller than their constituency vote shares, suggesting that voters might have favoured the local candidate from these party, while casting their vote on the party-list ballot for another party.

Table 1. Constituency and Party-List Votes by Party

Party	Constituency Vote	Constituency Vote (%)	Party-List Vote	Party-List Vote (%)	Difference (percentage points)
Move Forward	9,739,144	25.8	14,438,851	38.5	12.7
Chart Pattana Kla	297,946	0.8	212,676	0.6	-0.2
Chart Thai Pattana	623,902	1.7	192,497	0.5	-1.2
Prachachart	441,420	1.2	602,645	1.6	0.4
Democrat	2,304,202	6.1	925,349	2.5	-3.6
Palang Pracharath	4,263,993	11.3	537,625	1.4	-9.9
Bhumjaithai	5,177,297	13.7	1,138,202	3.0	-10.7
United Thai Nation	3,624,170	9.6	4,766,408	12.7	3.1
Pheu Thai	9,428,774	25.0	10,962,522	29.2	4.2
Thai Sang Thai	963,413	2.6	340,178	0.9	-1.7

The phenomenon of ballot splitting becomes more pronounced when comparing the winners of constituency elections and party-list votes. A glance at the map displaying constituency election results (Figure 1) reveals a patchwork of political parties. Yet, when the same map is used to visualize the parties that won the highest party-list vote in each constituency, Thailand transforms into a sea of orange and red, depicting big wins for the MFP and Pheu Thai, respectively. The latter remains the party of choice in most of the Northeast, but the MFP has emerged as a dominant force in most of the rest of the country, extending its influence across central and northern Thailand, even making surprising inroads into the traditionally conservative southern regions.

Figure 1. Constituency Vote Results vs Party-List Vote Results

In 186 constituencies, different parties emerged victorious in the party-list and constituency systems (Figure 2), indicating that ballot splitting led to discrepancies in the outcomes in nearly half of all constituencies. Strikingly, in many cases, the two parties that emerged victorious in each constituency were not ideologically aligned. For instance, the MFP, a stridently progressive political party strongly opposed to the military-backed government of General Prayut Chan-o-cha, placed first in the party-list vote in 34 constituencies won by the Bhumjaithai Party, 23 constituencies won by Palang Pracharath, and 13 constituencies won by the United Thai Nation. All of these parties had supported General Prayut’s government.

Figure 2. Heat Map of Winning Party in Constituency vs Party with Most Party-List Votes

As individual voter preferences cannot be directly inferred from these aggregate findings, the cause behind ballot splitting remains open to multiple interpretations. One possibility is that voters who split ballots have dual, sometimes divergent preferences. They may prioritize candidates who can address local issues effectively, regardless of party affiliation. Simultaneously, they also consider parties’ popularity, policies, and leadership. This interplay between local and national concerns could result in varying strength of partisan attachments among voters across parties and constituencies.

Alternatively, these dynamics may also stem from a deliberate campaign strategy aimed at securing the constituency vote first and foremost. In our fieldwork conducted in northern Thailand, we observed candidates running under the PPRP’s banner engaging in localizing the election. They avoided emphasizing their party label, which could have provoked backlash due to the party’s association with the junta, and also steered clear of actively promoting their unpopular prime ministerial candidate, General Prawit Wongsuwan. Instead, these candidates focused on highlighting their personal qualifications, taking credit for local contributions, and mobilizing support through vote-canvassing networks.

However, not all candidates were equally successful in leveraging the two-ballot system to engineer ballot splitting and secure victory in constituency elections. In fact, even influential political dynasties (baan yai) such as the Asavahames in Samut Prakan, the Khunpluems in Chonburi, and the Pitutechas in Rayong lost constituency seats to the MFP and trailed far behind it in party-list elections (Table 2). This indicates that neither the dual preference nor the localized campaign strategy, if these factors were at play, were sufficient to produce ballot splitting in favour of candidates opposed to the MFP in these provinces.

Table 2. Comparison of Performance by Local Dominant Party and Move Forward Party in Select Provinces

Province	Local Dynasty and Dominant Local Party	Seats Won by Dominant Local Party	Constituency Vote for Dominant Local Party	Party-List Vote for Dominant Local Party	Constituency Vote for Move Forward	Move Forward Party-List Vote
Suphanburi	Silpa-archa Clan (Chart Thai Pattana Party)	5/5	227,983	110,046	107,295	182,211
Buriram	Chidchob Clan (Bhumjaithai Party)	10/10	389,929	165,026	176,172	267,776
Petchabun	Prompat Clan (Palang Pracharath Party)	6/6	229,092	19,910	112,290	193,197
Kamphaeng Phet	Varathep Rattanakorn Faction (Palang Pracharath Party)	4/4	150,611	19,768	91,956	144,037
Uthai Thani	Thaiseth Clan (Bhumjaithai Party)	2/2	93,030	27,234	34,267	64,188
Chonburi	Khunpluem Clan (Pheu Thai Party)	1/10	281,194	209,896	318,857	435,509
Samut Prakan	Asavahame Clan (Palang Pracharath Party)	0/10	160,167	24,476	372,740	447,751
Rayong	Pitutecha Clan (Democrat Party)	0/5	101,932	26,231	179,087	230,729

The two-ballot system provides voters with greater flexibility and choice in expressing their preferences, for example, enabling them to choose a candidate from one party based on local considerations, such as the candidate’s track record, or personal ties to their constituency, while simultaneously voting for another party on the party-list ballot that aligns with their broader ideological or policy preferences.

In Suphanburi, Buriram, Petchabun, Kamphaeng Phet, and Uthai Thani, entrenched political dynasties won every constituency in their provinces. Yet, on the party-list ballot, none came close to matching the MFP’s performance. The presence of divided loyalties in these strongholds may not necessarily reflect the baan yai’s strength but rather their desperate struggle for survival.

In 2011, Chart Thai Pattana was only 15,303 party-list votes apart from the biggest party-list vote winner in Suphanburi, which was Pheu Thai. However, this gap increased to 72,165 votes in 2023, with Move Forward. Worse, voting for Chart Thai Pattana and Pheu Thai on different ballots is not necessarily indicative of a divergent preference — both could plausibly end up in the same coalition — but the same could not be said for Move Forward.

While ballot splitting has enabled these baan yai to survive this time, it is not clear that they will be able to avoid the same fate as their counterparts in Samut Prakan, Chon Buri, and Rayong in subsequent elections. The MFP’s success in converting party popularity into constituency wins, demonstrated in 112 constituencies, hints at a portent of doom for political dynasties. In all but two of these constituencies, there was no room for two parties to prevail, and, quite possibly, there will be no return to old-style politics either.

2023/173