Armenia's parliament is set to elect Armen Sarkissian as president to succeed Serzh Sarksyan, who opposition leaders say could become prime minister and continue to wield power.

Sarkissian's election to a single seven-year term is unopposed because the ruling Republican Party supports him even though he is not a member of any party. One opposition party says it will back him while another has failed to gather sufficient votes to present its own candidate.

Armenia seceded from the Soviet Union in 1991 but remains dependent on Russia for aid and investment. Many Armenians accuse the government of corruption and mishandling an economy that has struggled to overcome the legacy of central planning.

Sarksyan became president at an election in 2008 and nominated former Prime Minister Sarkissian in January to succeed him as his term neared its end. Sarkissian, 64, is a businessman and Yerevan's ambassador to Britain and the president said he had chosen him because of his experience as a diplomat and manager. The legislature can elect a president with a three-quarters majority under the terms of a constitution approved in 2015 in a referendum that effectively abolishes direct presidential elections.