Three of the four ethnic-based parties in Ethiopia's ruling coalition, the Ethiopian People's Revolutionary Democratic Front or EPRDF, voted Thursday to become one single party.
The newly formed party, created just months ahead of the general election in May, is called the Prosperity Party.
Prime Minister Abiy Ahmed said in a statement that Prosperity is "committed to strengthening and applying a true federal system, which recognizes the diversity and contributions of all Ethiopians."
The Tigrayan People's Liberation Front or TPLF, which dominated EPRDF before Abiy became prime minister, refused to participate in Thursday's vote.
"The whole process is a total sham," said Getachew Reda, a senior TPLF member. The prime minister didn't follow the right procedures . . . it was wrong as well as undemocratic."
Last month, TPLF warned in a statement that a merged party would "put Ethiopia on the road to disintegration."