By LYDIA POLGREEN
 
ORT-AU-PRINCE, Haiti, Feb. 25 — When opposition leaders formally announced Wednesday that they had rejected a peace plan the United States had hoped would end the uprising roiling the country, they took pains to emphasize that they have no links whatsoever to the armed groups sweeping through Haiti.

But it was clear that the success of the insurgents, who on Sunday took Cap Haitien with little resistance from supporters of President Jean-Bertrand Aristide, has buoyed their movement.

"This is all the more reason for Mr. Aristide to go," said André Apaid, a leader of the Group of 184, a civil society organization, in an interview on Wednesday. "This is all the more reason to press harder for what we see is the only way out, and it is only more clear that we need to do this very, very quickly."

As Haiti's crisis lurches toward civil war, a tangled web of alliances, some of them accidental, has emerged. It has linked the interests of a political opposition movement that has embraced nonviolence to a group of insurgents that includes a former leader of death squads accused of killing thousands, a former police chief accused of plotting a coup and a ruthless gang once aligned with Mr. Aristide that has now turned against him. Given their varied origins, those arrayed against Mr. Aristide are hardly unified, though they all share an ardent wish to see him removed from power.

In Port-au-Prince, meanwhile, pro-Aristide forces were trying on Wednesday to shore up control, erecting burning barricades and blocking main traffic routes with concrete tank traps and shipping containers.

Tensions were running high, with armed police officers, some wearing ski masks, roaring through town in pickup trucks, while sinister bands of teenagers wielding rifles guarded makeshift roadblocks, searching cars and stealing whatever they wanted from passengers.

In Belle, an earthy, staunchly pro-Aristide neighborhood about five minutes walk from the Presidential Palace downtown, a group of youths sat and played cards, waving occasionally as groups of chimères, the president's fearsome militiamen, sped by in trucks.

Groups of people chanted, "Five years, five years!" as the militiamen passed, a rallying call referring to the president's insistence he serve out his five-year term of office, ending in February 2006.

"Let the rebels come, we are not afraid," said Jean Toussaint, one of the youths. "They have guns, yes, but we do, too."

"We'll attack them with knives and machetes," he said."We'll slit their throats — they'll never make it to the palace."

On one side of those lined up against Mr. Aristide and his supporters are political and civic opposition groups, which have led huge protests in the capital and elsewhere, and have been subjected to violence by the police and progovernment gangs. Born out of the disputed parliamentary elections in 2000 and galvanized by political violence aimed at protesters, the groups came together as the Democratic Platform.

On the other side are the armed insurgents, many with sinister pasts. The uprising began in Gonaïves with a revolt by former Aristide loyalists, known as the Cannibal Army, who turned against the president after their leader, Amiot Métayer, was killed in September. The group, which is now led by Mr. Métayer's brother Butteur, believes Mr. Aristide ordered the killing.

They have been joined by members of the former Haitian Army, which was dissolved after the United States returned Mr. Aristide to power in 1994. The ranks of the insurgents include men like Louis-Jodel Chamblain, who is accused of killing thousands of people in the aftermath of the 1991 military coup that removed Mr. Aristide, and Remissainthe Ravix, a former army corporal notorious for his brutal methods.

The opposition groups with which the United States hoped to broker a peace deal, the Democratic Platform and several political parties, say they have no connection to the armed groups that have taken control of much of the country. In a statement released on Wednesday in response to the latest peace proposal, the Democratic Platform wrote that it "reaffirms that it has no ties whatsoever to armed groups and that its quest for a democratic solution is based on a strategy of nonviolence."

Those leading the armed uprising in turn affirm that they have no formal links with the political opposition, but Guy Philippe, who is leading the rebel army, hinted that the groups do have an open line of communication.

"Officially, there is no contact," Mr. Philippe said Tuesday in Cap Haitien, Haiti's second-largest city. Asked if there were unofficial links, Mr. Philippe smiled but would not answer.

Mr. Aristide has repeatedly said that the two groups are working in concert, though he has provided no concrete evidence to back the allegation. The leaders of the armed group said they had not been involved in negotiations for a political settlement of the country's crisis.

But whether or not there are links between the groups, the common goal of removing Mr. Aristide from power has led each to speak carefully about the plans and goals of the other. Asked about the armed insurgents, Mr. Apaid said he deplored the violence but did not expect the men to put down their weapons until Mr. Aristide left office.

"Otherwise they would be slaughtered," Mr. Apaid said. Asked about the role they would seek in a future government if Mr. Aristide was ousted, Mr. Philippe and other rebel leaders have said they have no interest in imposing military rule and that they support a plan put forward by the Democratic Platform. That proposal calls on political parties, businesspeople, intellectuals and civil society groups to form a transition government of national unity. His men, Mr. Philippe said, would become the nucleus of a reconstituted Haitian army.

Such odd bedfellows are not uncommon in Haiti's troubled history said Henry Carey, a professor at Georgia State University who is an expert on Haitian politics. But they seldom bring good fortune to the Haitian people.

"Haitians learned through history that the way to change their government is intimidation and protest, not through elections and democratic procedure," Professor Carey said. Even if there are no formal links with militants, he said, "the opposition groups have been too eager to make alliances with anyone who wants to get rid of Aristide without carefully examining their democratic credentials. That means inevitably the most lethal elements are the ones who will grab power when the time comes."