Lebanon's opposition will boycott a parliament session tomorrow meaning the planned election of a new president cannot happen.
Politicians failed to agree a on who will replace the pro-Syria incumbent, whose term ends tomorrow.
The anti-Syrian governing coalition said this evening it would go to the session to elect a replacement for President Emile Lahoud. But the boycott by the Damascus-backed opposition means there will be no two-thirds quorum for the vote.
Despite Mr Lahoud's support for the opposition's claim that the government of Prime Minister Fouad Siniora is illegitimate, many fear his departure with no deal on his successor could result in violence.
Mr Lahoud and the opposition say the Siniora government lost its legitimacy when all its Shi'ite ministers resigned last year.
French-led efforts to forge agreement between the coalition and the opposition, which includes the powerful Hezbollah have failed.
The election has already been postponed four times and there are fears that a country racked by a 1995 - 1990 civil war could slip see rival administrations claiming legitimacy.
The coalition is already arguing that Mr Siniora's government would automatically take over presidential powers until a new head of state is elected.
But Mr Lahoud has said he will take action before leaving office if there is no deal. Although he has not said what he plans to do, one option is asking the army to take over.
"I stand by my position that this government is illegitimate and unconstitutional. If it thinks it can go on without the election because of outside backing, it will bring catastrophes on the country sooner or later," Mr Lahoud told a Hezbollah-led delegation.
The governing coalition rejected as unconstitutional a proposal by Christian opposition leader Michel Aoun for him to name a candidate for the presidency.
The president must be a Maronite Christian in Lebanon's sectarian power-sharing system and Mr Aoun insists the presidency is rightfully his.
But he said the candidate, whom he did not name, would not belong to his parliamentary bloc and would be replaced after legislative elections in the spring of 2009.