As soon as the government fell, both sides defended their positions.

After a meeting, Mr. Hariri’s bloc released a statement, expressing a willingness to compromise. But the statement, read by Boutros Harb, a lawmaker and minister, added, “There’s no way to compromise on the issue of the court and justice.”

Hezbollah refused to comment until Thursday. But an allied official, Health Minister Mohamad Jawad Khalifeh, said: “We don’t want any escalation. We are committed to the Constitution. We don’t know what commitment the others are talking about.”

In a crisis that pivots on questions of prestige, the resignations provided a hint of theater. The energy minister, Gebran Bassil, flanked by nine other opposition ministers, announced the resignations at the same time that Mr. Hariri was in Washington to meet with Mr. Obama. The opposition had hoped that all 11 ministers would have resigned by the time of the meeting, as a way to embarrass Mr. Hariri, who would have had to enter the meeting as, at best, a caretaker prime minister. In the end, Mr. Hussein, the 11th, did not make it in time.

For months, Hezbollah has warned it would not stand by as its members were accused of involvement in the assassination, sensing that that would damage its reputation and open it to possible international legal action. Though it is technically part of the opposition, its power in Lebanon as a single force is almost uncontested, owing to the maintenance of its alliance with a powerful Christian general and the fracturing of its rivals.

In contrast to 2005, Hezbollah’s adversaries  gathered around Mr. Hariri  have fewer options and less support than they once did, emblematic of the vast changes in Lebanon’s political landscape over the past few years. While the Bush administration wholeheartedly backed Mr. Hariri and his allies then, Mr. Obama has not pledged the same broad support.

Syria, whose influence was waning in 2005, has re-emerged in Lebanon, and even its detractors here have sought some kind of relationship with it. Most Lebanese also vividly recall the speed with which Hezbollah and its allies vanquished their foes in just a few days of street fighting in Beirut in May 2008.

The ministers’ decision to resign came after the collapse of talks between Saudi Arabia and Syria aimed at easing political tension. The two countries have backed rival camps in Lebanon since 2005 and their initiative was seen across the political spectrum as the best chance to end the stalemate. But on Tuesday night, Michel Aoun, a former general and a Christian ally of Hezbollah, announced that the two sides were unable to reach an agreement.