The leader of Aontú believes that Fianna Fáil and Fine Gael would work together to form a government to avoid another general election.
It comes amid the ongoing government formation talks.
Both Sinn Féin's Mary Lou McDonald and Fianna Fáil's Micheál Martin are continuing their separate efforts to reach a deal with other parties.
Fine Gael and Fianna Fáil have repeatedly ruled out working with Sinn Féin, but any government is likely to need the involvement of two of those three parties.
Speaking to The Hard Shoulder this evening, Deputy Peadar Tóibín said he believes Leo Varadkar and Michael Martin could face pressure from their TDs if a political stalemate continues.
He said: "I do think that if Fianna Fáil and Fine Gael backbenchers are faced with another election they will go into government with each other - I have absolutely no doubt about that.
"The problem I have at the moment is that Leo feels he must be coy about this - because he feels if he rushes into any sort of deal, his core will be really annoyed and angry with him."
He said he doesn't believe Fianna Fáil will go into government with Sinn Féin as long as the party is led by Micheál Martin - suggesting it's an "impossibility under that leadership".
Meanwhile, People Before Profit has said it's not afraid of another general election.
A number of left-wing TDs met with Sinn Féin today to discuss a potential programme for government.
Richard Boyd Barrett said that progress was made, but that a number of issues still need to be ironed out.
Speaking after the meeting, he said: "We're not afraid of another election if Fianna Fáil and Fine Gael are trying to sabotage the movement for change.
"Indeed, when you think about a 62% turnout doing this much damage to Fianna Fáil and Fine Gael one point we'd say is get out and start registering to vote.
"[If there's] a 70 or 75% turnout if there is another election, we could do even more damage to Fianna Fáil and Fine Gael."
