The Social Democratic and Labour Party and Sinn Fein were considering whether to enter into a pact in an attempt to maximise the nationalist vote.
Sinn Fein chairman Mitchel McLaughlin said he believed their parties - which are both pro-agreement - could win 11 of the 18 Westminster seats with a joint strategy.
But discussions between them ended on 20 March without a deal and afterwards, both parties criticised the other.
" I think people can draw their own conclusions as to Sinn Fein's motivation "
Alex Attwood, SDLP
SDLP chairman Alex Attwood said Sinn Fein's motivation for the meeting was "suspect".
"Sinn Fein, for all their talk about a ten year electoral strategy, couldn't or wouldn't outline what the strategy was for the next ten weeks, up to the Westminster and local government elections," he said.
"I think people can draw their own conclusions as to Sinn Fein's motivation."
Mr Attwood also said Sinn Fein had not explained how trying to replace unionist MPs who were essentially absentee, and who had failed to deliver for their constituencies with other MPs who were absentee, would improve things.
This was a reference to Sinn Fein's policy of refusing to take its seats in the British parliament.
" Brid Rodgers will need a map and a driver to take her into that constituency "
Mitchel McLaughlin, Sinn Fein
But its chairman Mitchel McLaughlin said the accusation was a "red herring" and the SDLP's attendance at Westminster was only 3%.
He said Northern Ireland got very little input at Westminister and his party was arguing for an island-wide strategy.
"We do believe that over the ten year period that we have outlined, there will emerge a very strong debate on the constitutional question," he said.
"It's imperative on nationalists to make sure they maximise their representation.
"We believe this is the countdown to a united Ireland."
Mr Attwood said Sinn Fein was arguing for the old sterile politics of the past.
Going back to the Westminster election he said that people knew his party's candidates in west Tyrone and north Belfast were the only ones who could knock out anti-Agreement or absentee sitting unionist MPs:
"They are Brid Rodgers and Alban McGuinness.
"They are the contenders to knock out the sitting unionist MPs.
"That's going to become a more compelling choice over coming weeks and it's one that will be proved correct," he said.
Mr McLaughlin said the message from the SDLP was clear and both parties would now prepare to contest the elections.
In terms of west Tyrone he said Pat Doherty was already elected for that constituency as an assembly member and knew the issues and the people.
"Brid Rodgers will need a map and a driver to take her into that constituency," he said.
"In north Belfast the recent polls speak for themselves and Sinn Fein is in poll position."