Lebanon's president warned Saturday he will not cede power to the US-backed prime minister if parliament fails to elect a successor, a move that could plunge the country into a constitutional vacuum. President Emile Lahoud, who is allied with Syria, insisted on a new "national unity" cabinet that would choose a successor acceptable to the country's deeply divided political factions, said the president's spokesman, Rafik Shalala. But Prime Minister Fuad Saniora, who is already facing an opposition campaign to oust him, has vowed to take over if the president's office becomes vacant. "If there is no election for some reason ... the government will assume responsibility and its main preoccupation will be to ensure election of a president," Saniora said in an interview with al-Arabiya last week. Parliament is responsible for choosing a new president before Lahoud's term runs out Nov. 23, but it has not met for three months because its speaker, who is allied with Lebanon's opposition movement, has refused to convene a session. If there is no president, the constitution calls on the prime minister and his Cabinet to assume his duties. But some in the opposition, which is led by the Shiite Muslim Hizbullah guerrillas, are calling on Lahoud to appoint another administration; a move the majority says amounts to a coup. The leaders' non-compromising positions are certain to deepen the country's political crisis and raise historical fears about the creation of two competing governments. In 1988, when Lebanon was in similar straits, the army and administration split in a dispute that ended in one of the last battles of the 1975-1990 civil war. The majority anti-Syrian coalition swept into power in 2005 and has been trying to oust Lahoud, seen as one of the anchors of Syria's continuing influence in the country. They hold a slim majority in parliament and see their chance to elect one of their own to the post. But the opposition has vowed to reject any candidate they don't approve of and is threatening to boycott any vote. The president's spokesman would not say whether Lahoud would appoint a rival administration before he leaves office, but made it clear he would not cede power to Saniora. "The president's position is clear: he will not hand over the country to a government over which there is a radical dispute among a large segment of the Lebanese people," Shalala said on the private LBC television station. "He (Lahoud) considers the Saniora government illegitimate and unconstitutional," he added. All five Shiite Muslim ministers and one allied Christian resigned from the Cabinet last November. Since then, Lahoud, the parliament speaker and the opposition have refused to recognize the Saniora government, maintaining it violated the constitution because it lacked Shiite representation. Shiites make up about one-third of Lebanon's 4 million people and are believed to be the country's largest sect. The current political crisis has taken on an increasingly sectarian tone and erupted into street battles earlier this year that killed 11 people. The president's warning that he will not cede power to Saniora came a day after a meeting with Cardinal Nasrallah Sfeir, the spiritual leader of the influential Maronite Catholic Church who is attempting to head off the crisis. The church has a special interest in the presidency, a post traditionally held by a Maronite under Lebanon's sectarian-based division of political power - making Lebanon the only state in the overwhelmingly Muslim Arab world with a Christian head of state. Sfeir has expressed hope that the presidential election will be held "on time."