The Socialist Party has ended its membership of the United Left Alliance.
It announced the move in a statement on its website.
The party said it did so “with regret” as it had initiated the negotiations that led to the ULA and its TDs were “genuine in our preparedness to work with others on the left in a respectful, democratic and principled fashion”.
“However some in the ULA, including TDs, have moved away from a principled left position and have ditched the collaborative spirit. Apart from the Socialist Party, the other groups in the ULA have accepted this situation, leaving us with no choice but to withdraw,” the statement said.
Socialist Party MEP Paul Murphy said last week that the party’s TD Joe Higgins had “downgraded participation” in the ULA.
The ULA was launched in November 2010 when the Socialist Party, People Before Profit and the Tipperary-based Workers Unemployed Action Group came together in what Mr Higgins then described as a “left alternative to the establishment parties”.
Five TDs were elected under the banner in the last general election, including Socialist Party candidates Mr Higgins and Clare Daly.
Ms Daly left the Socialist Party last September primarily due to disputes over her close political relationship with Mick Wallace after it emerged the developer and Independent TD for Wexford had made false VAT returns.