Two candidates will contest the 28 November by-election for the seat left vacant by the death of former Tongan Prime Minister 'Akilisi Pohiva.
Matangi Tonga reported Mr Pohiva's son Siaosi had registered to stand, as had environmental scientist Netatua Pelesikoti Taufatofua.
During the 2017 general election 2731 votes were cast in the Tongatapu 1 Constituency with the late 'Akilisi Pohiva winning 1376 of those.
Dr Taufatofua, who came second in that poll, was recently admitted to an International Scientific Advisory Panel for the World Meteorological Organisation and was once the Director of the Climate Change Program at the regional environmental group, SPREP.
Siaosi Vailahi Pohiva is an educational assessment specialist who has worked for the Secretariat of the Pacific Community.