Lebanon's turmoil worsened on Friday with rival political camps failing to find a consensus that would allow parliament to choose a new head of state before pro-Syrian President Emile Lahoud's term expires at midnight.
Many fear Lahoud's departure from office with no successor could lead to two competing administrations and violence in a country still rebuilding from its 1975-1990 civil war.
Lawmakers from the Western-backed majority plan to go to a parliamentary session due to convene at 1 p.m. (1100 GMT), but they are not expected to elect a president in the face of a declared boycott by the Hezbollah-led opposition.
The opposition boycott means the chamber cannot command a two-thirds quorum for a vote already postponed four times.
I don't expect any surprises in parliament, majority MP Mohammad Kabbani said. There will be no election by an absolute majority... and I don't expect any surprises in the street.
An opposition political source said Parliament Speaker Nabih Berri would cite the absence of a quorum to postpone the vote again and call for a new session in about a week's time.
French-led mediation has failed to forge agreement on Lahoud's successor between groups opposed to Syrian influence in Lebanon and others backed by Damascus, including Hezbollah.
There are fears for the future. I am from the generation which lived through the civil war, which destroyed our dreams, said Charbel Faris, an artist. Enough, said the 55-year-old, urging the politicians to end the crisis. We've had enough of dancing on the blade of a sword.
Thousands of Lebanese soldiers and police, backed by armored vehicles, deployed across Beirut overnight, lining some streets leading to parliament in downtown Beirut. Others guarded government buildings or manned checkpoints.
Extra measures were taken around a five-star hotel where dozens of anti-Syrian lawmakers have been staying under guard for the past two months for fear of assassination attempts.
Lebanon has been rattled by some 30 politically motivated attacks over the last three years that have killed dozens, including eight anti-Syrian politicians and journalists.
The army has warned against any internal strife. Both sides have accused each other of arming their supporters.
Lahoud disputes the legitimacy of the Western-backed government of Prime Minister Fouad Siniora and has said he will take action before leaving office, without giving details.
The former military chief has previously suggested he might hand over his powers to General Michel Suleiman, the current army chief. The governing coalition would reject such a step.
The president must be a Maronite Christian, according to Lebanon's sectarian power-sharing system.
The anti-Syrian majority argues that Siniora's government should automatically take over presidential powers until a new head of state can be elected, a view supported by European foreign ministers visiting Beirut on a mediation drive.
The United States and its local allies blame Syria for the deadlock. Hezbollah and its Christian allies say the U.S.-backed majority wants to keep them from their rightful share in power and accuse Washington of trying to control Lebanon.
French Foreign Minister Bernard Kouchner left Beirut on Thursday after the latest of several failed mediation efforts.
(Additional reporting by Nadim Ladki; Writing by Alistair Lyon; Editing by Dominic Evans)