'Rise' will be the name of TD Paul Murphy's new political party, which was launched this afternoon.
It stands for 'radical, internationalist, socialist and environmentalist’, and was formed after a split in the Socialist Party.
Mr Murphy is the group's only elected official and says he will stay within the Solidarity - People Before Profit banner in the Dáil.
Deputy Murphy acknowledges some people will see it as the left fracturing again.
He said: "I will understand people thinking that, to people who are a distance from the left, these debates may seem a bit obscure, I understand that.
"I think watch what we say, watch what we do, let things play out over a number of months and I think the differences in strategy will become clear to people."
Paul Murphy at the announcement of the new political party. Pic: Rollingnews.ie