Lebanon's caretaker prime minister said on Monday he would not take part in any future government headed by a Hezbollah-backed candidate, raising the stakes in a political crisis that many fear could descend into violence.
Saad Hariri made the announcement as President Michel Suleiman began two days of consultations with lawmakers over their choice of premier.
Lebanon will likely see lengthy negotiations to form a new government after Hezbollah toppled Hariri's Western-backed unity government on 12 January over his refusal to renounce a UN-backed tribunal investigating the 2005 assassination of his father, former Prime Minister Rafik Hariri.
Many fear Hezbollah will react violently if its members are indicted, as is widely expected.
Hezbollah, which gets support from Syria and Iran, is Lebanon's most powerful armed force.
Now, both sides are scrambling for enough support to form a government.
Hezbollah and its allies, known as the March 8 bloc, were believed to have chosen moderate politician and billionaire businessman Najib Mikati as their candidate.
Mikati, who served briefly as premier in 2005, announced late on Sunday that he was seeking the post as a candidate of "moderation and accord."
After Monday's meeting with Suleiman, Mikati presented himself as a consensual candidate, reaching out to all sides.
"I am extending my hand for all, for the interest of all Lebanon, without any exception," he said, adding that he wanted to "work together" with Saad Hariri "for the sake of Lebanon."
Mikati dodged a question over whether he would end Lebanon's cooperation with the international court - a key Hezbollah demand - saying only that any dispute can be solved only through dialogue.
A statement issued by Hariri's office, however, said there was no "consensual candidate."
"There is a candidate named Saad Hariri and another candidate for the March 8 forces and the choice in this regard is clear and unambiguous," the statement said.
Hariri said his Future movement would not participate in any government headed by a Hezbollah-backed candidate.
The support of at least 65 lawmakers is required to form a government in Lebanon's 128-seat Parliament.
Hezbollah and its allies already claim 57 seats.
Saad Hariri has 60.
Walid Jumblatt, the influential leader of the Druse sect who heads an 11-member bloc in Parliament, said this week he was supporting Hezbollah and Syria.
He was believed to have secured for Hezbollah the votes of at least seven lawmakers from his bloc, which would bring the militant group only one seat short of majority to govern on its own.
The Hezbollah leader said on Sunday the group and its allies would seek to form a new unity government with their rivals in Lebanon's Western-backed political bloc if the candidate they were backing was chosen to be prime minister.
A Harvard graduate, Mikati is seen as a relatively neutral figure who enjoys good relations with Syrian President Bashar Assad and also with the pro-Western Hariri, who himself is seeking to keep the post.
Mikati, whose wealth is estimated at 2.5 (b) billion US dollars, is on the Forbes list of world billionaires.
In the 1980s, during Lebanon's civil war, he founded telecom company Investcom with his elder brother, Taha.
They sold the company to South Africa's MTN Group for 5.5 (b) billion US dollars in 2006.
The Mikati brothers now run M1 Group, a multi-billion dollar holding company with interests in telecom, oil and gas and real estate among other things.
Last year, M1 bought a 13.95 percent stake in Bank Audi, Lebanon's largest bank, for 450 (m) million US dollars.