There is now no elected successor and a bitter dispute looms over who is in power.
The pro-Syrian and anti-Western Lahoud left the presidential palace and he issued an order that the army should take over control.
However, pro-Western Prime Minister Fouad Siniora rejected the move and says that under the constitution he and his cabinet are in temporary power.
The president is elected by parliament, but a vote was scuttled by the pro-Syrian opposition who did not allow the necessary quorum to be achieved.
The election of a president requires a two-thirds majority, which means that the pro-Western ruling bloc--with only a slim majority--could not force its preferred candidate through parliament.
The streets reflected the chaotic mood with the army deployed in force and schools closed.
The US, Russia, Syria and Iran have all been intensely involved.
Russia should provide regional leadership and the U.S. should take a step back.