The Sinn Féin President has said she "strongly believes" that a coalition of left-wing parties can take the Government on and offer a "real alternative" to what is currently in power.
Mary Lou McDonald also said that the days of Fianna Fáil and Fine Gael "controlling both government and opposition at the same time are over" and people now want change.
Ms McDonald along with Labour TD Marie Sherlock, Sinead Gibney of the Social Democrats and PBP-Solidarity TD Ruth Coppinger took part in a panel discussion this afternoon entitled "Building a Common Left Platform".
The panel discussion formed part of The Robert Tressell Festival taking place at the Liberty Hall Theatre in Dublin today.
The discussion was chaired by UK Labour MP, Mary Kelly Foy.
In her opening address, Deputy McDonald cited the Government's handling of a number of issues including the revelations about unnecessary hip surgeries being carried out on children, proposed changes to the so-called Triple Lock, and the war in Gaza.
She also said: "There are big questions, challenges and opportunities and I do believe that parties on the left can work constructively and effectively together.
"Maybe more to the point, I believe the parties of the left have to work together effectively and constructively," the Sinn Féin president added.
Meanwhile, Deputy Gibney, the Social Democrats TD for Dublin Rathdown, said there are lots of reasons why there needs to be a collaboration of parties on the left.
She said: "First and foremost, it is to exert pressure, and I think we have seen that already how that has been successful in this early Dáil term in terms of speaking rights, in terms of just this week with Cara Darmody and the issue around assessment of needs."
Ms Gibney also said that she had been "most disheartened" as a new TD by the "constant undermining" of the opposition by Fianna Fáil and Fine Gael.
She went on to say: "Most importantly, as opposition parties, the reason that we have to work together is to present a real alternative.
"Because attaching junior parties from the left to a Fianna Fáil and Fine Gael or a both led government, we have seen how detrimental that is to the growth of the parties," she added.
In her opening address, Deputy Ruth Coppinger said: "It is clear that the force that is creating the far-right is capitalism itself."
She said: "Therefore, a common left platform has to be a challenge to capitalism and the ideas of capitalism because that is what is creating the basis for the far-right."
Deputy Coppinger said this had particularly been created in Ireland by a "decade-long housing crisis".
Meanwhile, Deputy Sherlock of the Labour Party said the need for a common left platform has never been more "blindingly obvious".
She said: "I think there is enormous potential for us all here to paint a picture of a credible, workable alternative but the political will has to be there."
Ms Sherlock went on to say that: "If we're truly serious about building an alternative, then I think we really need to reflect on how we do business, both in the Dáil, on the airwaves and across our communities.
"Some of that co-operation is already happening on housing, on Gaza, on additional needs as we saw already in the Dáil this week," Deputy Sherlock added.
