* Lebanese MPs may submit blank voting slips
* Syria war dividing Lebanon's religious sects
* Delay in choosing president would worsen political vaccuum
By Laila Bassam
BEIRUT, April 22 (Reuters) - A majority of Lebanese parliamentarians may submit blank voting slips on Wednesday in the first ballot for a new president, political sources said, as they struggle to agree on a consensus candidate after months of violence and political deadlock.
Parliament has been summoned to choose a successor to President Michel Suleiman, whose six-year term ends in late May, but deep divisions over the war in neighbouring Syria could delay any decision, possibly for several months.
Putting off the choice of president could add to a political vacuum in Lebanon, which is struggling to contain domestic sectarian conflict while also grappling with a flood of Syrian refugees and a sharp slowdown in economic growth.
Lebanon's presidency is reserved for the country's Maronite Christians under a confessional system aimed at sharing representation among its many religious communities.
But the war in Syria has split Lebanon's Christians just as it has divided Muslims. Shi'ites support Syrian President Bashar al-Assad and Sunnis mainly back the rebels.
The leading Maronite to declare his candidacy so far is Samir Geagea, a vocal opponent of Assad who is expected to be backed - at least in the first round - by the anti-Assad March 14 coalition, led by Sunni Muslim former premier Saad al-Hariri.
Geagea, 61, spent 11 years in jail for political murders and other killings during Lebanon's civil war, the only warlord imprisoned after the conflict ended in 1990.
The rival March 8 political bloc, led by militant Shi'ite group Hezbollah which is fighting in Syria to support Assad, has indicated it would back former army chief Michel Aoun.
Aoun, a Hezbollah ally trying to portray himself as a consensus figure in contrast with Geagea, has yet to declare himself formally in the running.
March 14 and March 8 sources say that means Wednesday's vote is likely to be inconclusive, with Geagea unable to garner the two-thirds support necessary for a first-round victory - or the 50-percent-plus-one vote needed in any subsequent count.
"Wednesday's session will not bring a new president, but it might pave the way for consensus options, including Michel Aoun," one March 8 source told Reuters, adding that many parliamentarians would hand in blank papers.
OTHER POSSIBLE CANDIDATES
Geagea is expected to win between 45 and 50 votes in the 128-seat parliament, well short of the 86 needed to win outright in the first round.
That could open the way for Aoun and other candidates - including the current army chief and the central bank governor - to nominate themselves as candidates in future rounds of voting.
Army commander General Jean Kahwaji would be following a well-trodden path if he were to join the race. Both Suleiman and his predecessor President Emile Lahoud led Lebanon's armed forces before switching to political office.
Riad Salameh, central bank governor for more than two decades, has earned international respect for steering Lebanon's economy through the turbulent post-year wars, managing the country's high debt levels and keeping the currency stable.
Although the Taif agreement which ended Lebanon's 1975-1990 civil war transferred some powers from the Maronite president to the Sunni Muslim prime minister, the presidency remains an influential role in Lebanon.
In the last months of his term Suleiman has increasingly criticised Hezbollah's military intervention in Syria - a stance which almost certainly cost him any chance of an extension to his six-year mandate.
His successor will have to help maintain stability in a small country hosting more than a million Syria refugees and hit by car bombings, rocket attacks and street fighting which killed scores of people in the last year.
He will also have to pave the way for a parliamentary election later this year which has been delayed for months by the same political impasse which threatens to drag out the choice of a new president.