Hours after Prime Minister Omar Karami and his cabinet announced their resignation on Monday, Lebanon's myriad political groupings began tense negotiations over who would run a caretaker government to oversee a parliamentary election scheduled for May. With parliament almost evenly split between pro-Syrian loyalists and the opposition, the Iranian-backed Hezbollah looks to hold the deciding seats.

The opposition is now actively appealing to the militant group to remain true to its roots as a liberation movement and join the push to oust Syria from Lebanon. In recent remarks, Walid Jumblatt, one of the main leaders of the anti-Syrian opposition, has gone out of his way to praise Hezbollah's head, Sheik Hassan Nasrallah, as a "great leader," and has repeatedly called on him to join the opposition.

"There is a lot of contact with Hezbollah going on right now," said one opposition figure familiar with the talks, who spoke on condition of anonymity.

Under the country's constitution, whoever President Émile Lahoud nominates for the post of prime minister needs to be approved by a majority of the country's 120 parliamentary deputies. In the meantime, Mr. Karami remains in office with reduced powers.

The opposition, which claims the support of the tens of thousands who have demonstrated in central Beirut almost every day since the assassination of former prime minister Rafik Hariri on Feb. 14, will likely put forward his sister, Bahia Hariri, as its candidate for prime minister.

According to the Lebanese constitution, the prime minister must be a Sunni Muslim, with the cabinet made up of equal numbers of Muslims and Christians. Ms. Hariri is Sunni.

Her candidacy would be widely popular on the streets, and would be a symbolic blow to both Mr. Lahoud and his political masters in Damascus. The opposition has accused the Lebanese and Syrian regimes of playing a role in Mr. Hariri's slaying, which a United Nations team is investigating.

Ms. Hariri's political star was seen as tied to her brother's throughout his 10 years as prime minister. But the schoolteacher-turned-MP has emerged as one of the leaders of the opposition since her brother's assassination. She gave an emotional speech to parliament on Monday that was cited by Mr. Karami as one of the reasons he finally decided to resign.

Although several former Syrian loyalists have crossed the floor in the past two weeks, the opposition still lacks the numbers necessary to push her candidacy through parliament. With the remaining pro-Syrian legislators reportedly dug in against such a partisan choice, the opposition would likely need the backing of Hezbollah and its 12 deputies to install Ms. Hariri as prime minister.

Considered a terrorist organization by the United States, Hezbollah has close ties to Damascus but has so far remained neutral in the power struggle between pro- and anti-Syrian forces.

While joining the burgeoning democracy movement might seem an odd fit for the Iranian-backed militant group, Mr. Nasrallah recently acknowledged having regular meetings with Mr. Hariri in the months before his assassination.

Beyond their desire to make Ms. Hariri prime minister, the opposition wants Hezbollah onside to fix the opposition's nagging image problem. While Christian, Druze and Sunni Muslim groups have all united to demand an end to interference from Damascus in the wake of Mr. Hariri's death, there's little Shia representation in their ranks. Hezbollah is Lebanon's largest Shia political movement, while the other major force is the staunchly pro-Syrian Amal party headed by parliamentary speaker Nabih Berri.

"If Hezbollah sides with the opposition, we have effective unanimity. Otherwise, we are missing one of the major sects in Lebanon: the Shiites," the anonymous opposition figure said. "It could be dangerous if they oppose us."

Farid Chedid, a political analyst and editor of the lebanonwire.com website, said Hezbollah is in a tough spot, not wanting to damage its ties with Syria, which has helped funnel money and weapons to its fighters in southern Lebanon, but also not wanting to be seen standing against the will of the Lebanese.

"Hezbollah is split between its loyalty to Syria and its desire to support liberation and independence," Mr. Chedid said. In the end, he added, Hezbollah would likely get its orders on how to behave from Tehran, which probably means standing fast in its backing for Syria.

Though Beirut has largely returned to normal in the wake of Monday's jubilant street party after Mr. Karami's resignation, several hundred protesters were still camped in tents on the central Place des Martyrs square yesterday, promising not to go home until Mr. Lahoud also resigns and Syria withdraws the 14,000 soldiers it has stationed in Lebanon.

Syria's troops entered Lebanon, ostensibly as peacekeepers, in the second year of the 1975-1990 civil war. Syrian forces remained in the country after the conflict ended, and have dominated Lebanese politics ever since.

Syrian President Bashar Assad said this week that Syrian troops might pull out in the next few months, a key demand of the Lebanese protests. The opposition reacted to the statement yesterday with skepticism.