Samoa's ruling Human Rights Protection Pary, or HRPP, will be the only party to contest this month's Anoama'a West by-election.
The opposition Samoa Democratic United Party says it won't nominate a candidate, repeating its policy of focusing on the general elections next year.
The party has asked why the government doesn't decide which of its candidates will get the seat and avoid the expense of having a by-election.
The three candidates are a former speaker, Leota Itu Au Ale; a former justice department head and Apia lawyer, Fonotoe Nuafesili Lauofo and Gaugau Mateo Ah Tong, who is the principal accountant of the Ministry of Health.
All three candidates ran unsuccessfully in the last general elections, in 2001.
