By TONY SMITH
 
ORT-AU-PRINCE, Haiti, Feb. 21 — Despite political arm-twisting, the top American diplomat for the Western Hemisphere left Haiti without reaching a deal with the political opposition to share power with President Jean-Bertrand Aristide.

A diplomat involved in the talks, which lasted several hours, said the results were unclear but that the political opposition would respond on Monday. The situation is fraught because armed groups are also seizing ground to challenge Mr. Aristide.

Assistant Secretary of State Roger F. Noriega and other top diplomats from the Americas and Europe spent the day here pushing an urgent proposal to replace the current government with a multiparty cabinet, while allowing Mr. Aristide to complete his term in office.

Despite hours of hard negotiating, the opposition refused to budge, insisting that Mr. Aristide must resign immediately. At one point during talks with a group of opposition leaders, one diplomat could be seen hammering the table with his fist. But the visiting diplomats evidently had few inducements to offer the opposition.

"The plan calls for us to build a government with Mr. Aristide, but that is not acceptable," said Rosemond Pradel, leader of one opposition group, who briefly left the talks in a luxury, hillside hotel.

The president, while backing the plan, again insisted that he would complete his term that ends February 2006.

Mounting political tensions have turned into violent rebellion over the past two weeks as armed groups opposing Mr. Aristide have clashed with the government's outnumbered and outgunned police force and brutal, armed gangs used by the president to impose his political will on the long-suffering populace. The violence has compounded a longstanding rift between the pro-Aristide parties and his mainstream political opposition.

More than 60 people have died in the clashes and a swath of territory — from the coastal city of Gonäives across the Central Plateau to the border with the Dominican Republic — has been wrested away by rebel troops, virtually cutting the country in two.

The State Department this week advised Americans to leave the country, and long lines of anxious missionaries and aid workers have formed at Port-au-Prince's international airport in recent days.

Diplomats are anxious to hammer out a political deal because the alternatives are unpalatable. Either Haiti would slide into civil war, setting off a humanitarian crisis and a wave of refugees to the United States, or external military action would be needed to stabilize the country.

A diplomat on the sidelines of the talks said he feared the impasse would continue, despite the fact that "both sides have had the riot act read to them." But even if an agreement were reached, he warned, it would not take into account the the armed groups that have gained control over a good part of the country.

On the ground, many ordinary Haitians said they would welcome international intervention.

"We need America's help," said Augustin Francique, a resident of Hinche, a central town occupied by rebels last week. "If God has failed to protect us against Aristide's gangs, then only the Americans can do it."

That, for now, however, does not appear to be on the American agenda.

As the hours ticked away, the diplomats came close to missing a deadline to leave Haiti on board a Canadian government plane that, because of Canadian government regulations could not stay unguarded on the ground in a hostile environment overnight.

At the root of the problem is the abyss of mistrust between Mr. Aristide and his political opponents.

After meeting the visiting diplomats on Saturday, the president said "we are ready to work with our brothers in the opposition to protect the constitutional order," but he also called rebel forces "terrorists and murderers" and indicated he would like to have international support to disarm their forces.

On the other hand, opposition forces are adamant that they will only accept what they call "option zero" — the immediate resignations and, preferably, exile of the former parish priest.

Mr. Aristide was viewed as a hero when first elected in 1990 on a platform of succoring Haiti's downtrodden, who had suffered not only poverty but also daily terror at the hands of previous dictators. After being ousted in a coup in 1991, he was returned to power by the threat of an American-led invasion in 1994 and enjoyed massive popular support across the country.

But that popularity has soured as the president failed to deliver on promises to improve the lives of the poor and, instead, began to govern with the methods of his despotic predecessors.

Today, 70 percent of Haitians are jobless and more than half thought to be undernourished.

Chavannes Jean-Baptiste, once a fervent Aristide supporter who turned against his former ally in 1997, said the president was "sick for power."

Now an influential opposition leader — his peasant movement counts 200,000 members across the country — Mr. Jean-Baptiste says the opposition cannot trust the president.

"Even if God were to organize elections here, Jean-Bertrand Aristide would somehow steal the ballot," he said.

In Washington, the State Department ordered the withdrawal of all nonessential American personnel and family members from the embassy in Haiti. The department also repeated a warning that American citizens who are not on government business in Haiti should leave while commercial air service continues to operate on a regular basis.

According to The Associated Press, the department said the warning was based on a determination that "the security situation in Haiti has deteriorated to unsafe levels."

"Americans are reminded of the potential for spontaneous demonstrations and violent confrontations," the statement said.