PORT-AU-PRINCE, Haiti, Feb. 14 Rene Preval, whose support among the poor masses has made him the favorite to become Haiti"s next president, stepped out of the silence he began after the election last week to charge Tuesday that "massive fraud and gross errors had stained the process."

Still, he urged the throngs of people who had paralyzed cities with flaming barricades and protests to end the violence and continue demonstrating peacefully.

"The Haitian people are frustrated," Mr. Prrval said. "They have a right to be frustrated. And they have the right to protest. But we must respect private property. We must respect the law. We must respect the rights of others.

"Do not give in to anger. Today, let"s conduct politics intelligently, without violence."

At a news conference at his sister"s house in Peguy-Ville, a hillside suburb, Mr. Pr?al rejected election results released so far that showed him with a wide margin against his nearest opponent, but slightly short of the 50 percent plus one vote that he needs to avoid a runoff. He said the tabulations had been rigged against him, but he and his supporters offered little in the way of evidence.

In the name of his coalition, Lespwa, the Creole word for hope, Mr. Pr?al demanded that electoral authorities withhold announcing the final results, which had been expected Tuesday but were delayed until Wednesday, for a transparent recount.

"If you publish the results the way they are now," Mr. Pr?al said, "Lespwa will contest, and the people will contest."

The warnings and calls for calm, live on radio and television stations, seemed to have almost immediate effects. Leaders of the interim government and foreign diplomats worked on plans for a review of the tabulations. United Nations troops began clearing away junked cars, heavy boulders and burning tires blocking the main thoroughfares here. Traffic began crawling where angry protesters had roamed. Markets began bustling with shoppers. And small demonstrations felt more like parties than protests.

"Now I feel happy," said Denis Constant, one of a few hundred people who danced through Canap?Vert on Tuesday afternoon. "I don"t know whether he will be president. But I think things will all work out."

It was unclear to most people how the saga surrounding the elections on Feb. 7 would end. The contests, organized by an interim government, installed by the United States and backed by 9,000 United Nations troops, were widely considered crucial to restore a semblance of democracy to a country whose institutions have been wrecked by a long history of dictators and whose people were sucked into a new cycle of upheaval two years ago when an armed uprising ousted President Jean-Bertrand Aristide.

The elections had seemed to pull Haiti back from the brink of civil war. After a tumultuous start, large numbers of people waited for hours to cast their ballots without a serious incident of violence. But the tabulation and accusations from political camps that tally sheets were manipulated have re-ignited old fights.

Political analysts close to the negotiations that started after violence flared Monday indicated that a special commission could be formed by foreign diplomats, the interim government and the United Nations Stabilization Mission in Haiti to review the tabulations. Michel Brunache, director of the cabinet of the interim president, said in an interview that the commission would not include foreigners, but representatives of the Provisional Electoral Council, from Mr. Pr?al"s Lespwa party and from the government"s executive branch..

To prevent violence, Mr. Brunache said, the government made an agreement with Mr. Pr?al to withhold the final results until the commission had finished its review.

"During these elections, Haitian people showed their desire to advance democracy," Mr. Pr?al said, referring to a turnout estimated at more than 60 percent. "The people are convinced I won in the first round. But when they saw the votes for me begin to decline, it was like a cruel hoax. Their hope turned to anger."

His camp offered no numbers or documents to refute conclusively the results so far, which show him with 48.7 percent of an estimated 90 percent of the ballots. Suspicions seemed to focus on an estimated 85,000 blank votes and 120,000 voided ballots, of about 2.2 million votes that election officials said had been cast.

Advisers to Mr. Pr?al suggested that tens of thousands of Haitians would not have walked hours or stood in line to cast blank votes.

Those ballots, by law, have been included in the net totals. Without them, Mr. Pr?al would have, so far, won more than 51 percent of the vote.

Some people, however, see the large number of blanks as reflecting broad contempt for their government ?which has done little to lift this country out of extreme poverty ?or of people"s disfavor for all 33 presidential candidates.

Mr. Pr?al"s advisers also expressed concerns about an estimated 8 percent of the ballots that are missing, at least half believed lost or stolen. The advisers pointed out the wide discrepancies between the results announced by the government and those predicted by independent international organizations.

A slow-count sample of the results by the National Democratic Institute showed that Mr. Pr?al would win in the first round, with 52 to 54 percent of the votes. A ballot survey by the Organization of American States showed that Mr. Pr?al would win an estimated 55 percent of the votes.

"We have solid arguments that the results by the government do not reflect reality," said Bob Manuel, an adviser to Mr. Pr?al who was loosely translating the candidate"s words for the Spanish-speaking news media. "We are asking them to wait so we can present evidence."

Residents from a violent slum, Cit?Soleil, near Titanyen, 20 miles north of the capital, said they found mounds of ballots dumped there, most supporting Mr. Pr?al.

Cit?Soleil is a Pr?al stronghold. A spokesman for the United Nations mission here, David Wimhurst, said the ballots could have come from one of the nine voting centers trashed on Election Day. But he could not confirm that. Other than the images of thousands of pages of documents, the discovery had not been confirmed. After the scenes of the discovery were broadcast on television, there were reports of barricades going back up in scattered parts of the capital and of gangs of young men on motorcycles screaming threats.

As for Tuesday, all tabulations stopped. A high O.A.S. official said work at the central tabulation center stopped because barricades kept technicians from reporting in.