By Jim Muir
BBC News, Beirut
Just a few days before its legislators are due to elect a new president, nobody in Lebanon knows what lies in store and whether the election will even go ahead.
Mr Ghanim is the eighth anti-Syrian figure to be killed since 2005
The assassination on Wednesday of anti-Syrian parliamentarian Antoine Ghanim has pitched the country into even greater uncertainty and tension.
He is the seventh anti-Syrian figure, and the fourth member of the current parliament, to be assassinated since the killing of former Prime Minister Rafik Hariri in February 2005.
That event triggered enough Lebanese and international outrage and pressure to induce Syria to pull its troops out of Lebanon after nearly 30 years there.
Damascus was widely blamed for Mr Hariri's death and the subsequent violence, as it has been for Mr Ghanim's death, but has consistently denied any involvement and condemned the killings.
Anti-Syrian MPs would like to see the issue resolved swiftly, not least because they fear that if the crisis drags on, more MPs will be killed
Its withdrawal from Lebanon, carried out in the shadow of the US invasion of Syria's neighbour Iraq and amidst fears that Damascus could face a similar fate, led to new elections and the formation of an anti-Syrian government in Beirut.
But now, the balance of regional power is seen to have shifted.
The US is floundering in Iraq and its Israeli allies are perceived to have failed in their war against Hezbollah in Lebanon last year.
Balance of power
Most observers agree that the turmoil in Lebanon - as in the Palestinian territories and Iraq - reflects that struggle over the regional balance of power and an attempt by forces opposed to the US and Israel to reassert themselves on the local scene, with the support of regional backers Syria and Iran.
That struggle is now focused on the issue of the Lebanese presidency.
The current incumbent, Emile Lahoud, who is obliged to hand over the job on 24 November, is regarded as firmly in the pro-Syrian camp.
Feb 2005: Ex-PM Rafik Hariri
April 2005: MP Bassel Fleihan
June 2005: Anti-Syria journalist Samir Kassir
June 2005: Ex-Communist leader George Hawi
Dec 2005: Anti-Syria MP Gebran Tueni
Nov 2006: Industry Minister Pierre Gemayel
June 2007: Anti-Syria MP Walid Eido
Sep 2007: Anti-Syria MP Antoine Ghanim
The anti-Syrian coalition, which enjoys a small and dwindling majority in parliament, is determined that Mr Lahoud's successor should not come from the Syrian-backed opposition, whose main candidate at present is the maverick former general Michel Aoun.
Some of the anti-Syrian group - known as "March 14" after the date of a mass rally in 2005 seen as a key turning point in the campaign to oust the Syrians - are in favour of a neutral consensus candidate, while others insist that the new president must reflect their nationalist views.
Neither side can muster the two-thirds majority to elect a president on a first ballot.
But some of the March 14 faction favour falling back on a simple majority of 50% plus one vote (65 out of the chamber's nominal 128 seats) if agreement cannot be reached with the minority opposition on a compromise candidate.
Such a move would clearly court dangerous repercussions. The spearhead of the pro-Syrian opposition, Hezbollah, has a military capability probably stronger even than the Lebanese Army.
It has been besieging the government palace in central Beirut since last December with impunity, and has threatened unspecified consequences if the anti-Syrian majority try to impose its own president.
If parliament cannot elect a successor to Mr Lahoud, he should in principle hand his powers to the government when his mandate expires in late November.
But given its anti-Syrian hue, he is thought likely to set up a rival administration - leading to another dangerous scenario of division and disputes over official buildings and ministries.
The Speaker of Parliament, Nabih Berri, had set 25 September as the date for MPs to convene and elect a new president, a simple procedure if agreement has been reached behind the scenes.
There is no such understanding so far, but recent weeks have been peaceful and a reconciliation initiative over the presidency launched by Mr Berri - part of the pro-Syrian camp - has received a positive reception by many of the factions.
In the days before the 25 September vote, Mr Berri had been expected to hold a significant meeting with Maronite Christian Patriarch Nasrullah Sfeir - a highly influential figure in the current scenario, since the presidency by tradition goes to a Maronite.
He was also expected to meet Saad Hariri, the Sunni leader who heads the March 14 coalition and who had called for the election to be consensual and unanimous.
Both those meetings have been postponed in the wake of the Ghanim assassination, further reducing the chances of a deal before the 25 September session of parliament.
But Mr Berri has said the session will go ahead, and the March 14 anti-Syrian faction has called on all its members to attend.
They would like to see the issue resolved swiftly, not least because they fear that if the crisis drags on into November, more MPs will be killed to reduce their already paper-thin majority, which is down to less than a handful of votes.
The anti-Syrian deputies are already taking extraordinary security precautions, and part of a luxury hotel near parliament has been reserved for their use before the meeting.
But tensions are high, and there are fears that violent attempts could be made to stop parliamentarians reaching the chamber in downtown Beirut.
The March 14 coalition has called on Mr Berri to have a nearby Hezbollah camp removed before the session. Mr Berri is allied to Hezbollah, but it seems unlikely the movement will comply.
The most likely scenario is that parliament will meet, fail to muster the necessary two-thirds quorum (because opposition MPs will not turn up) and be postponed to a later date.
But a move by the March 14 faction to elect a president by a simple majority cannot be ruled out.
Much may depend on the manoeuvres of outside powers, which are deeply embroiled in Lebanon's affairs.
While most have supported Mr Berri's initiative - based on electing a consensual president with a two-thirds majority - the US appears to favour a simple majority vote that would let the anti-Syrian faction claim victory whatever the dangers.
Anti-Syrian Lebanese MP
Member of Maronite Christian Phalange party
Elected deputy in 2000
Re-elected in 2005
"The US is the main player in Lebanon," said analyst Amal Saad Ghorayeb of the Carnegie Foundation.
"March 14 basically answer to the US. Even when they try to act on their own initiative, when American officials make their position clear, the coalition immediately changes.
"There's a clear pattern of foreign diktat here. But there could be a sudden shift of position at the very last moment."
Others would level similar accusations of clientship at Hezbollah and its allies in their relationship with Syria and Iran.
Washington is engaged in mounting acrimony with Iran over its nuclear programme and activities in Iraq.
It has also been stepping up pressure on Syria, which was hit by an obscure Israeli air strike on 6 September amidst US allegations that it may be engaging in nuclear activities.
Can Lebanon's crisis be resolved in isolation from regional tensions involving powerful players deeply embroiled in its affairs?
The prospects were never very rosy, though the possibility was, and still is, there.
But the ruthless and violent assassination of Antoine Ghanim has made the future look even more bleak.