Sisaket By-Election – Key Popularity Test for Pheu Thai and Bhumjaithai

The upcoming August 10 by-election in Sisaket’s Constituency 5 will be the first major test of the government’s popularity since Bhumjaithai exited the coalition and Paetongtarn Shinawatra’s premiership fell into crisis following the leaked tape from former Cambodian Prime Minister Hun Sen. It is also a must-win for the government, which currently holds a slim majority in the House—so slim that nearly every session becomes a frantic scramble to round up MPs to make a quorum and avoid a collapse of the sitting.

The by-election will replace Pheu Thai MP Amorntep Sommai, a three-term MP and local businessman who recently passed away. In the 2023 general election, Amorntep defeated Bhumjaithai’s Theera Traisoranakul in a fairly close race, winning by around 7,000 votes. Notably, the constituency lies on the Cambodian border, where voters are likely to have felt the impact of the ongoing bilateral dispute that has disrupted trade and engulfed the prime minister and her party.

The contest will be a “battle of the daughters,” with Pheu Thai’s Phurika “Kung” Sommai and Bhumjaithai’s Jintawan “Ajarn F” Traisoranakul—both daughters of the 2023 candidates—standing as new-generation leaders from influential political-business clans. Phurika has started a Facebook page for her campaign, announcing her candidacy and readiness to walk in her father’s footsteps. Jintawan is currently Chairwoman of the Sisaket Provincial Tourism Industry Council and previously served as a legislative aide. She also has a Facebook page. The People’s Party has announced it will not field a candidate, citing its expectation of a forthcoming House dissolution and general election.

Pheu Thai and Bhumjaithai have dominated recent elections in Sisaket. Pheu Thai won seven of the province’s nine seats in 2023, while Bhumjaithai secured the remaining two. More recently, in the February 2025 Provincial Administrative Organisation (PAO) election, Bhumjaithai’s Wichit Traisoranakul—Theera’s brother and the incumbent—defeated Pheu Thai’s Wiwat Chai. Former seat holder Pheu Thai’s Amorntep won his seat in 2001 under Chart Thai Pattana, in 2005 as a member of Thai Rak Thai, and in 2023 representing Pheu Thai.

Both parties are expected to pour considerable resources into this contest, including high-level political sponsorship and funding. Paetongtarn campaigned in Sisaket during the 2023 election, chanting on stage: “Chase out the rat (Anutin) and beat the cobras (defecting MPs),” though she later formed a coalition with Anutin. It would fit again now that Anutin has joined the opposition, but Pheu Thai may not want to remind voters of its own about-face. With Pheu Thai’s popularity sinking in national polls, the backing of party heavyweights may also do little to lift its local candidate. If Bhumjaithai wins the seat it will be able to more credibly claim the political tide is moving in its direction—which is crucial, given the government’s precarious position and the opposition’s growing strength.