The Democratic Unionist Party operates in 17 constituencies, stepping aside in Fermanagh's southern Tyrone in support of the ultra-unionist candidate Tom Eliot.
Sinn Fein is running in 15 constituencies and will not be running for candidates in South Belfast, East Belfast or North Down and will instead support candidates for the remaining seats. In the meantime, the Ulster Unionist Party will run in 16 constituencies.
The Alliance is the only political party to lead candidates in all 18 constituencies. DUP won 10 seats in last election and Shane Jane won seven, along with independent Silvia Eileen.
A total of 102 candidates will compete in 18 constituencies across Northern Ireland at this year's General Election. The nominations closed Thursday before voting day for next month.
Steve Aiken the UUP had earlier suggested the party run in all 18 constituencies in the region. He later withdrew from that position after pressure in North Belfast and unionist rivals over a candidate against the Democratic Unionist leader's deputy. Nigel Dodds, who is expected to face a close race against Sinn Fein Finon Funchane.
The other constituency in which the UUP will not run is West Belfast, a place traditionally dominated by Sinn Fein with only a small margin of trade unionists. Aiken has also been pressured to keep his party in South Belfast, where the DUP is Emma Little Pengel is expected to come under pressure from the SDLP candidate Claire Hannah.
The Green Party withdrew to South Belfast for Hannah over her Remains.
Meanwhile, the SDLP announced it has completed the nomination of the 15 candidates it will have. The party had earlier said it was stepping aside in three constituencies to support the remaining candidates. These are North Belfast, East Belfast and North Down.
The Green Party is stepping aside in the East, West and North Belfast in support of the remaining candidates.
Of the smaller parties, the People Before Profit has two candidates, the NI Conservative Party is debating four seats and Auntu will be a candidate in seven constituencies.