The March 14 bloc's win will reassure its supporters in Washington and Saudi Arabia, while the opposition defeat is a blow for Iran and Syria, which support Hezbollah and were hoping to counter US influence in Lebanon.
But protracted negotiations over the composition of a new national unity government could spark a fresh political crisis between the two rival camps.
A key sticking point is what should be done with Hezbollah's weapons – a question that has been at the crux of the political schism in Lebanon since the devastating month-long war with Israel in 2006. "It depends how smart March 14 plays it," says Ousama Safa, director of the Lebanese Center for Policy Studies in Beirut. "The election result has ripped many cards from Hezbollah ... but if March 14 has learned anything, it would be a major mistake to go after Hezbollah's weapons head-on."
Initial statements by March 14 leaders have struck a magnanimous tone, congratulating the opposition for a hard-fought race and expressing a readiness for cooperation and compromise.
While waiting for final results Sunday night, Walid Jumblatt, a March 14 leader and chief of Lebanon's Druze community, said that the opposition could not be sidelined from a future government.
"In case of a March 14 victory, we must not isolate the others," he said. "Beware of the deadly mistake of isolation."
The results of the election began to trickle through late on Sunday evening when it emerged that the March 14 bloc was gaining the upper hand in some of the key constituencies north of Beirut, in the southern town of Sidon, and in the Bekaa Valley, which were widely seen as the decisive battlegrounds in what has been the closest-fought election in over three decades.
As the results streamed in during the early hours Monday, fireworks exploded in the night sky above Beirut while motorcades of jubilant March 14 supporters drove up and down streets honking their horns.
Results reverberate in Riyadh, Tehran
The final results delivered early afternoon Monday confirmed March 14 was the winner with 71 seats in the 128-seat parliament, which included two allied independent candidates, against the opposition's 57 seats.
The margin of victory was larger than predicted, with analysts suggesting that the arrival of some 100,000 expatriate Lebanese in the days before the election swayed the result.
"I think the expatriate voters tipped the balance. They were the external variable in the elections," says Mr. Safa.
The results will bring sighs of relief and gasps of dismay from governments in cities as far removed as Washington; Tehran, Iran; Jerusalem; and Riyadh, Saudi Arabia. Although a tiny country, Lebanon plays a pivotal role in the broader regional struggle pitting Iran, Syria, and their allies Hezbollah and Hamas against the US and its Middle East friends, such as Saudi Arabia and Egypt, who fear Tehran's growing influence in the Arab world.
The term of the present parliament expires on June 21. Once the new parliament is seated, it will vote for a speaker of parliament, a position that in Lebanon's sectarian system is traditionally occupied by a Shiite. Nabih Berri, who has been speaker since 1992, is expected to be reelected to the post. The next step involves the president, Michel Suleiman, holding discussions with lawmakers on who should be appointed the next prime minister, traditionally a Sunni. Sources close to Saad Hariri, the head of the Future Movement and a leader of the March 14 coalition, have indicated that he will run for the post.
Crux of political schism: Hezbollah's weapons
Once the prime minister has been selected, formal consultations begin on the composition of the next government. However, initial contacts between the rival camps were expected to begin as soon as the final election results were confirmed Monday afternoon.
Hezbollah's priority in the coming negotiations is to ensure that a future government will not represent a threat to its formidable military wing.
"The majority [March 14] must commit not to question our role as a resistance party, the legitimacy of our weapons arsenal, and the fact that Israel is an enemy state," Mohammed Raad, a Hezbollah member of parliament, told Agence France-Presse Monday. "The results indicate that the crisis will continue, unless the majority changes its attitude."
Hezbollah insists that its weapons are necessary to deter future Israeli aggression, but its opponents argue that only the Lebanese Army has the right to bear arms and only the state can decide on matters of war and peace.
When the government attempted to shut down Hezbollah's private military communications network in May 2008, it triggered the worst bout of internal violence since the end of the 1975-90 civil war. The fighting ended with an agreement brokered in Doha, the capital of Qatar, which led to the formation of a new government of national unity in which the opposition held a veto-wielding one-third share. The veto power allowed the opposition to block legislation with which they disagreed, such as further attempts to disarm Hezbollah.
The March 14 coalition reluctantly accepted the arrangement, but argued that the veto power stifled government activity. Still, the Doha agreement bought a year of calm in Lebanon during the run-up to Sunday's election.
Emboldened March 14 coalition likely to pressure Hezbollah
The March 14 bloc says that while it favors a new national unity government with opposition participation, it will not repeat the offer of a veto.
"Clearly, the majority does not want to repeat the paralysis of the past year," says a senior March 14 source who spoke on condition of anonymity. The source says he doubted that Hezbollah would provoke a crisis over the one-third veto share, asking, "what is their justification?"
But some analysts believe that a new crisis is in the making with an emboldened March 14, encouraged by the US and by the scale of its electoral victory, to pursue Hezbollah's disarming.
"This result will be seen as a victory for the US and Israel. There will be more pressure on Hezbollah to disarm than before," says Amal Saad-Ghorayeb, an expert on Hezbollah.
She added that Hezbollah would consider it "imperative" that it retain the veto power in the next government.
"The outcome of the election is entirely to the benefit of the US and Hezbollah will want to mitigate that by ensuring it has the one-third veto," Ms. Saad-Ghorayeb says.