UN chief Ban Ki-moon is holding talks in Lebanon to try to break the impasse over electing a new president.
Mr Ban said Lebanon was going through critical times
The secretary general is to meet members of the pro-Western government, and officials from Hezbollah, which is backed by Syria and Iran.
On Thursday he met the head of the Maronite Church, Nasrallah Sfeir.
Parliament is scheduled to convene by the end of next week to elect a successor to President Emile Lahoud whose term ends on 23 November.
The vote has already been postponed three times to give rival leaders more time to agree on a candidate.
This deadlock has caused the worse internal political crisis in Lebanon since its 1975-90 civil war.
There are fears that the government could split into rival administrations if a candidate cannot be agreed.
Under Lebanon's power-sharing system, the president must be a Maronite Christian.
Mr Ban is bolstering a French-led initiative to break the deadlock.
"The election of the new president should take place on time and in accordance with constitutional procedures," Mr Ban said.
"In this endeavour, it is imperative that the parliament convenes in order to elect a new president. The new Lebanese president should enjoy the broadest possible acceptance so that he or she can represent all Lebanese people."
Parliament is scheduled to meet again on 21 November. Mr Lahoud says he will appoint an interim administration, headed by the army chief, if his successor is not in place.