The Congress won the Arkakong assembly seat in Nagaland in the repoll held on Friday, official sources said.
Its candidate Takatiba Masa Ao defeated Intiyanger of the ruling alliance partner Nagaland People's Front by a margin of 498 votes raising the Congress strength in the 60-member house to 22, officials said.
The result for the Arkakong seat is the last to be declared for the assembly.
The Election Commission had ordered the repoll after gross irregularities were detected during the February 26 assembly polls in the state.
The Congress ministry headed by S C Jamir was defeated in the polls following which the Neiphu Rio Democratic Alliance of Nagaland assumed office on March 6.
The results of Arkakong and Pungto Khipre were held back by the Election Commission though all other results had been declared.
The Pungto Khipre seat which utlimately went to the Bharatiya Janata Party on March 24 raised the party's tally to eight in the house.
The EC withheld the result of the Pungte Khipre seat after miscreants torched the ADC's office, where the counting was taking place.
The party position in the house now stands at Congress-22, NPF-19, BJP-8, NDM-4, Janata Dal (United)-2, Samata Party-1 and Independents-4.