Micheal Martin has said talks of a Fianna Fail merger with the Social Democratic and Labour Party (SDLP) to contest elections in Northern Ireland are a work in progress.
Speaking at his party's Think-In on Tuesday in Malahide, Co Dublin, Mr Martin said no formal decision was made, but made reference to the abstentionist policy of elected Sinn Fein MPs who do not take their seats in Westminster.
"The great scandal of the moment is that the anti-Brexit majority in Northern Ireland is not represented in the Assembly, they are not represented in the executive and not represented in Westminster.
"If people don't want to take their seats in Westminster they should not contest the election and they should leave it open to people who want to take their seats."
The two parties have talked about co-operating in the past, however these talks are part of a merger being discussed at the highest levels of both parties including SDLP leader Colum Eastwood and other senior officials.
When Mr Martin was asked if his party members would swear an oath and send their party members to Westminster, he replied he would not let members contest elections and not take their seats.
"We certainly wouldn't contest elections and then not take our seats, that's just blocking people who could represent the anti-Brexit majority in Westminster.
"We've made no decision in relation to the north, it is a work in progress, but we are engaged and we do accept the constitution of settlement of the Good Friday Agreement.
"That settlement is of the three relationships, the north-south relationship, the British and Irish relationship and the relationship between the communities.
"Although we have made no decision on that in the North just yet.
"I think Margaret Richie and Mark Durkan would have been able representatives for the anti-Brexit majority in Northern Ireland and they have been denied that representation in Westminster."
Mr Martin recently told Fianna Fail's ruling executive to expect developments on the party organising in the North next month.