The new election date set by speaker Nabih Berri is just four days before an Arab League summit in Damascus which some leaders are expected to boycott unless the Lebanon issue is resolved.
The parliament had been due to hold the vote on Tuesday, bringing in the presidency General Michel Suleiman, head of the army and a compromise candidate.
The impasse has paralysed much of government and has left the presidency vacant since the term of Emile Lahoud expired, producing bouts of deadly unrest in a country still rebuilding from its 15-year civil war.
It has also poisoned ties between Saudi Arabia and Syria, which back opposing sides.
Riyadh supports the Beirut governing coalition, along with Western countries including the United States, while Syria and its ally Iran back the opposition alliance led by Hezbollah.
Saudi Arabia's King Abdullah, Hosni Mubarak, the Egypt president, and King Abdullah of Jordan, are not expected to attend the Arab summit without a Lebanese president also being in attendance.
Suleiman's confirmation by parliament has been derailed by a row over the make-up of a cabinet to be formed after his election.
Parliament cannot convene to elect the president unless there is a deal between the opposing camps, providing the quorum necessary for a vote.