Chontida Asavahame, who was fifth on Bhumjaithai's candidate list, will not be able to replace former transport minister Saksayam Chidchob as an MP, as she has quit the party, a party source said.
Supachai Jaisamut, Bhumjaithai's registrar, said the party has informed the Secretariate Office of the House of Representatives of Ms Chontida's resignation, so she is not eligible to become the MP.
It is expected that Nanthana Songpracha, the next candidate on the party's list, will replace Mr Saksayam.
The seat was left vacant after Mr Saksayam quit as an MP after the Constitutional Court ruled on Wednesday he used a nominee to hide his ownership of a company that won government construction projects.
The court suspended him from his cabinet post on March 3 last year when the case was accepted by the court.
Ms Chontida on Friday posted a message on Instagram that she quit the Bhumjaithai Party so she could help her mother and focus on working for people in Samut Prakan.
Ms Chontida is the daughter of the late politician Chonsawat Asavahame and Nantida Kaewbuasai, head of the Samut Prakan Provincial Administrative Organisation.