Greece has been shaken by the decision of the smallest partner in the governing coalition, Democratic Left, to pull out of government.
It comes after coalition party leaders failed to reach agreement on the future of the national broadcaster.
Prime Minister Antonis Samaras closed the state broadcaster ERT last week to save money, provoking outrage among his left-wing partners. He wants to replace it with a smaller broadcaster.
Despite his party's withdrawal, the leader of Democratic Left, Fotis Kouvelis, has warned against a snap election, and says his party will continue to back reform, the BBC reports.
If it were to withdraw its backing, the two remaining coalition parties would have a majority of just three seats.
Coalition talks over closure of ERT
Mr Samaras and his two junior coalition leaders - Mr Kouvelis and Evangelos Venizelos, leader of Pasok - met for a third time on Wednesday to try to resolve their differences.
Both Mr Kouvelis and Mr Venizelos want public broadcasts to be restored.
After the talks broke up, Mr Venizelos said the situation was now "particularly crucial". Mr Samaras says he is determined to avoid new elections.