BY NANCY SAN MARTIN

SANTO DOMINGO, Dominican Republic - When President Hipólito Mejía held his last campaign rally last week, supporters pulled out a hen, suggesting that his main challenger in today's presidential election was a little too refined to govern.

Supporters of former President Leonel Fernández, the front-runner, shot back with a donkey, suggesting that Mejía is not smart enough to continue to hold the presidential seat.

By the eve of the election, the mudslinging escalated to serious allegations that Mejía's ruling party had tampered with the voter registration list, while Fernández was accused of being caught on tape urging an unidentified businessman to pull funds out of the country in an effort to create an economic panic.

The contentious campaign provides the backdrop for an election that is sure to draw a massive voter turnout when stations open this morning. Polling has consistently indicated that Fernández will win, but the gap has narrowed in recent polls and Dominicans living abroad also will play a role for the first time.

THOUSANDS ABROAD

An estimated 52,400 Dominicans are expected to cast votes in various U.S. cities, including Miami, as well as in Puerto Rico, Canada, Spain and Venezuela. Thousands more flew home to vote. There are more than five million registered voters in the country of 8.8 million.

In a nation with a history of dictatorships and manipulated elections, there is widespread concern that today's vote could be marred by fraud. But international and local leaders said they are optimistic the election will be carried out free of controversy.

''I expect it to be fair and transparent,'' U.S. Ambassador Hans Hertell said. ``The international community has put a lot of effort into this election.''

Msgr. Agripino Núñez Collado of the Roman Catholic church, who often serves as a mediator in national political conflicts, said: ``I have strong faith that on Sunday, the country will celebrate a day of democracy. It will not be a day of fear, but one with plain and absolute liberty.''

The latest poll, conducted by the Washington-based Gallup the first week of May, shows Fernández with 54 percent of the vote to Mejía's 30 percent. The wild card in the race, Eduardo Estrella, is trailing with 10 percent. The poll of 1,200 people had a 3 percentage point margin of error.

FRAUD SUSPICIONS

Suspicion of potential voter fraud has been fueled, in part, by a constitutional change last year orchestrated by Mejía's ruling Dominican Revolutionary Party (PRD) that allowed him to seek a second four-year term. The PRD holds a majority in the bicameral Congress.

Fear of violence also hovers if the election results in a loss for Fernández. Clashes among dueling supporters already have claimed nearly a dozen lives.

''The conflict here is real,'' said Luigi Einaudi, assistant secretary-general of the Organization of American States, one of several international organizations monitoring the elections. ``The Dominican Republic has real organized, effective political parties.''

FREEDOM OF PRESS

He added that freedom of press and expression ``helps relieve steam and avoid violence.''

More than 8,000 national and international observers will be dispersed to polling stations across the country.

The OAS, which will account for about 160 observers, has been working with the electoral council since February. Two trial runs on the computer technology that will be used to tally the votes have been successful, said Santiago Murray, chief of mission.

''The technical conditions are in place, so there should be no problems,'' he said.

Said Einaudi: ``From a technical standpoint, it will be possible to have a clean election. People should vote with confidence and not be derailed by conspiracy theories.''

MAJOR PROBLEMS

The winner in today's election will inherit the Caribbean nation's worst economic crisis in decades, marked by soaring inflation, a sharp devaluation in the Dominican peso, a large foreign debt, rising unemployment and an energy crunch that has resulted in hourslong power outages.

Mejía, 62, has blamed the country's economic woes on a world recession and a 2003 bank scandal that cost the Dominican treasury $2.2 billion. Mejía has said the bank problem was the result of lax oversight in the sector during Fernández's administration, which was in office from 1996 to 2000.

Since Mejía's term in office, the Dominican Republic's economy has nose-dived. Inflation topped 43 percent last year, the Dominican peso has lost half of its value, and the foreign debt has doubled from $3.7 billion in 2000 to $7.6 billion in 2003.

In his bid for a second term, Mejía has promoted his party's ''Now for the good times'' motto by promising to raise government minimum wage by 30 percent, build 400,000 new houses, increase food subsidies for the poor and double the number of single mothers who get government checks to help with their children's school supplies.

LOWER-TAX PROMISE

Mejía also promised to lower taxes by 10 percent for those in lower- and middle-income tax brackets and to do the same for businesses.

Campaigning under the ''Progress Is Returning'' slogan promoted by the Dominican Liberation Party (PLD), Fernández, 51, has promised to revive the economy by revisiting the tight fiscal policies of the late 1990s. During his term in office, the economy grew by 8 percent a year and the peso traded at 16 to the U.S. dollar, compared with today's 45 pesos to the U.S. dollar.

Estrella, meanwhile, has been heavily courted by Mejía and Fernández supporters. If neither of the leading candidates gets 50 percent of the vote, a runoff would be forced and the candidate backed by Estrella would gain a crucial boost going into the second round.

But at his final rally Friday, Estrella, 50, of the Reformist Social Christian Party, assured supporters he wouldn't lend his support to either candidate. His party has portrayed itself as the path to change, proclaiming, ``The population can't take any more.''

The new president is to take office in August.