Solidarity-People Before Profit TD Richard Boyd Barrett has said votes for the left have "disappeared" in its core bases for the local elections.
The party was put at just 2% in an RTÉ/TG4 exit poll by Red C.
Mr Barrett told Newstalk their base voters simply did not come out and vote.
"It's not a brilliant day by the looks of it - a lot of the seats that we're fighting for are going to come down to transfers.
"So it's going to be a long night I think for a lot of our candidates.
"But I think it's fair to say that the left in general has not done brilliantly well - and that seems to be very, very low turnouts in areas where we would have been strong and where parties of the left traditionally have been strong".
He quoted turnout figures between 20% and 10% in places like Tallaght, Ballybrack and Finglas - "places which would have had quite high votes for the left", Mr Barrett said.
"That vote has just disappeared, it hasn't come out today".
Green Party leader Eamon Ryan said earlier: "There is a green wave of public consciousness in Ireland, and we've been waiting for it for a long time."
"It's been happening throughout Europe and indeed other parts of the world - the Greens have been on the rise in Germany, Holland, Belgium, Sweden and all these countries - and it landed I think in Ireland in the last six months or a year."
On The Greens success, Mr Barrett added: "I think the vote for the Greens is obviously a vote for radical action - which I completely agree with on the climate emergency.
"I think the problem for us is our base has not turned out to vote - I think it would be a very different picture if it did.
"I see it as a good thing that people are expressing a desire for radical action on climate change, but I think there's also huge anger on issues like housing - but it hasn't come out and translated itself into votes".
"It has been a core issue on the door, without a shadow of a doubt, but strangely that has not translated into votes in the areas that are most affected by the housing crisis".