WASHINGTON – The fall of the Syrian-dominated government in Beirut has set off a struggle here that has the State Department, the Pentagon, Congress, and the Saudi ambassador each pressing plans for dealing with Syria’s occupation of Lebanon.

Among the ideas being floated:

* The State Department is eyeing a plan to expand the mandate of a United Nations force in southern Lebanon to the entire country.

* The Pentagon wants to step up its training of a unified Lebanese army.

* The Saudi ambassador, Prince Bandar, met with national security adviser Stephen Hadley Wednesday to tout a Saudi plan for Syria to leave Lebanon as a result of pressure from the Arab League.

* Rep. Ileana Ros-Lehtinen will introduce a bill next week calling for an international embargo on Syria, as well as American funding for assistance to individuals and groups “to support a transition to democracy in Syria.”

There has been considerable unity among world leaders calling for Syrian troops and security services to leave Lebanon since the government of Omar Karami collapsed Monday. Nonetheless, the question remains of who would replace the Syrian soldiers and spies should they leave the country.

While the proposals swirling around Washington are not necessarily mutually exclusive, the competing plans illustrate how American decisions could alter the course of the Cedar Revolution in the Levant.

Administration officials told The New York Sun yesterday that Foggy Bottom has started looking at expanding the mission of the U.N. Interim Force in Lebanon. The 1,994-person international force led by a French general, Alain Pellegrini, was created in 1978 during Lebanon’s civil war. In the 1980s and 1990s its primary purpose was to observe Israeli soldiers stationed in southern Lebanon. In the past, UNIFIL has come under harsh criticism from the U.S. mission at the United Nations because it has not taken action against the Syrian- and Iranian-supported Hezbollah militia.

Nonetheless, the State Department, buoyed by the recent support from France for statements calling on Syria to exit its neighbor, is exploring whether the U.N. force could be a stopgap measure to provide security for Lebanon’s May elections. “We are looking at ways Unifil could be enhanced in light of a Syrian withdrawal,” a State Department official said.

This source stressed that the idea was preliminary and that to date no diplomatic instructions were issued to the American mission at the United Nations. “We want the French to officially propose the idea because we are not in a position at this point to do it,” this official said.

When asked about the plan, a vice president of the American Enterprise Institute, Danielle Pletka, told the Sun, “If Unifil were to be expanded there would have to be very clear understandings about the role that it would have in confronting terrorist training camps and terrorist operations. If Unifil is only going to observe terrorists in action, as it does, it is not going to be much use.”

The Pentagon, on the other hand, is hoping to expand Lebanon’s national army and is looking to increase its training for the country’s military. The president’s supplemental budget request this year for International Military Education and Training significantly boosted funding for such projects, described in the 2006 budget request in part as “an important alternative to military training activities conducted together with Syria and other countries.”

“We have been hearing about expanded IMET training from the Pentagon since October, when the United Nations pushed for the Security Council resolution calling for foreign forces to leave the country,” a congressional staff member told the Sun. Another administration official confirmed that expanded training was under consideration but said that no decision had been made.

The question of what if any military force would replace the Syrian one in Lebanon has become a pressing matter in light of renewed pressure on Damascus from around the region to leave. Yesterday, the Syrian leader, Bashar al-Assad, flew to Riyadh for talks with Crown Prince Abdullah, and the Saudi leader asked for Mr. Assad to expedite the redeployment of forces. Riyadh was the location where Lebanese leaders and Mr. Assad’s father signed the Taif accords, which gave Syria a mandate to send peacekeepers to Lebanon in 1989. Under that agreement, Syrian forces were to be withdrawn by 1992.

The Reuters news agency quoted a Saudi official as saying that the crown prince told Mr. Assad, “Syria must start withdrawing soon, otherwise Saudi-Syrian relations will go through difficulties.” An administration official said

Prince Bandar also promised that his country would push for an Arab League resolution reiterating U.N. Security Council Resolution 1559, which calls for the removal of foreign troops from Lebanon.

“What the Saudis are trying to do is to tell the Syrians to get out of Lebanon. You can lose Lebanon without losing Syria. They are looking for a face-saving formula on this,” the Washington bureau chief for an Arabic newspaper, al-Hayat, Salameh Nematt, told the Sun.

Already, the crisis in Beirut has prompted some in Congress to begin calling for regime change in Syria. Ms. Ros-Lehtinen, a Republican of Florida, and Rep. Eliot Engel, a Democrat of New York, are planning to introduce the Lebanon and Syria Liberation Act. The legislation instructs the president to press for an international embargo of Syria in the United Nations and authorizes monies for individuals and nongovernmental organizations to press for a democratic transition in Syria. As the Sun reported Tuesday, Senator Brownback, a Republican of Kansas, is also considering funding for pro-democracy groups inside Syria. A staffer working on the House legislation told the Sun yesterday that they have yet to ask for comments from the White House on the bill.