Independent TDs Catherine Murphy, Róisín Shortall and Stephen Donnelly will formally launch a new political grouping on Wednesday.
Last month it emerged the three were in talks about an alliance.
In a statement on Saturday, the TDs confirmed they have been engaged in ongoing discussions for some time and have “agreed to launch an exciting new political venture”.
“We are excited to be working together to offer a new credible political choice to the Irish electorate,” they said.
It remains to be seen if they will form an alliance or a political party.
Ms Murphy is a high-profile TD for Kildare North who recently shot to national attention when she highlighted under Dáil privilege businessman Denis O’Brien’s dealings with IBRC, the former Anglo-Irish Bank.
Political sources have said Ms Murphy’s “brand” and ethical reputation is so strong, she does not require any alliance.
Politicised exercise
Mr Donnelly, who represents Wicklow, refused to sit on the banking inquiry, despite a direct appeal from the Taoiseach, believing that it was a politicised exercise in the run-up to the election.
Ms Shortall, a Dublin North West TD, resigned from the Labour Party in 2012. She stood down as minister of state for health following disputes with then senior minister James Reilly over primary care centres being located in his Dublin North constituency. All three are expected to retain their seats in the next general election.
While Mr Donnelly is seen as right-leaning in economic policy, compared to the left-leaning views of the other two TDs, all three would be left-of-centre on social policy and may form a social democratic-style party.
Minister of State Simon Harris, a constituency colleague of Mr Donnelly, said yesterday: “I’d wait and judge them on their policies”.
The move follows the establishment of a new political party Renua, led by former Fine Gael minister of state Lucinda Creighton.
Alliance
Meanwhile, Shane Ross and Finian McGrath are attempting to develop an alliance of Independent TDs and councillors.
Mr McGrath wished the grouping well in their new venue but said “the public are voting for independents and there are enough parties in the political system at the moment”.
He added: “Independents working together is a better option.”
The new grouping would compete with Mr McGrath’s alliance – and to a lesser extent with Renua – for the support of voters who say they do not support any of the established parties. That cohort has consistently ranked over 20 per cent in polls over the past two years.