PORT-AU-PRINCE, Haiti (AP) – Guarded by U.N. troops, mules carrying sacks of ballots trotted down from mountain villages Wednesday as authorities began the slow process of collecting and tabulating election results.

Scores of U.N. peacekeepers patrolled quiet streets of the capital, Port-au-Prince, as Haitians eagerly awaited the returns from Tuesday’s vote, the first since a bloody uprising ousted former President Jean-Bertrand Aristide two years ago.

The polls, guarded by the 9,000-strong U.N. force, were fraught with delays early in the day but largely free of the violence that has plagued the capital since Aristide fled.

The leading contender heading into the vote was Rene Preval, a 63-year-old agronomist and former president widely supported by Haiti’s poor masses. The shy, soft-spoken Preval, Haiti’s only leader to finish his elected term, is a former ally of Aristide, who is in exile in South Africa.

Preval’s closest rivals include Charles Henri Baker, 50, a wealthy garment factory owner, and Leslie Manigat, 75, who was president for five months in 1988 until the army ousted him.

More than 50 percent of the 3.5 million registered voters were believed to have cast ballots, said David Wimhurst, a U.N. spokesman, adding that a precise figure wasn’t yet available.

“I think no one can deny the legitimacy of this process because people really participated,” the special U.N. envoy to Haiti, Juan Gabriel Valdes, told Associated Press Television News.

However, he conceded that polls opened too late and “some people were not even able to vote.”

Senate candidate Myrlande Manigat, the wife of Leslie Manigat, said initial reports from party representatives monitoring the vote count indicate Preval has a big lead in her western district, which includes much of metropolitan Port-au-Prince and outlying areas.

“We are very worried that Preval has won on the first round,” Manigat told The Associated Press.

Preval was in his rural hometown of Marmelade and wasn’t speaking to reporters.

If no candidate wins a majority, a runoff between the top two vote-getters will be held March 19.

Election workers counted votes by candlelight overnight and resumed early Wednesday, Wimhurst said, adding that the process was gaining momentum but still going “very slowly” because of delays retrieving ballots from rural areas.

“The hardest part is getting ballots back to the capital,” where the vote tabulation center is located, he said. “In some cases, it will take two days to get ballots from outlying areas.”

To help the effort, U.N. officials are relying in part on 280 mules, some of which were loaded with bulging sacks of ballots and then led by handlers and U.N. troops from the countryside into towns. Later, the ballots were to be loaded onto helicopters that will carry them to the capital, Wimhurst said.

Initial results were expected to be released after 20 percent of the vote is counted, which could happen late Wednesday, said Stephan Lacroix, a spokesman for Haiti’s electoral council. Final results are expected later this week.

The huge turnout all but overwhelmed electoral officials, who conceded they were ill-prepared for the crush of voters.

Many Haitians voted Tuesday night after spending hours in lines stretching up to a mile at some polling stations.

Many stations opened late, lacking the necessary workers, security and ballots to handle the number of voters who turned out by foot, car and brightly colored buses.

“It could have been better,” Jose Miguel Insulza, head of the Organization of American States, said of the vote. But he said the enthusiasm of Haitian voters made the elections successful.

“In many places, people would not have stood in line for so long waiting to vote,” Insulza said.

The United Nations has not received any reports of fraud or other major irregularities in the voting, Wimhurst said.

The elections were deemed vital to averting a political and economic meltdown in the Western Hemisphere’s poorest nation. In the aftermath of Aristide’s ouster, gangs went on a kidnapping spree and many factories closed because of security problems and a shortage of foreign investment.