BY LESLEY CLARK

Democrat John Kerry enjoys a commanding lead over President Bush among Cuban Americans born in the United States and a decided edge among Cubans who arrived in the country after 1980, according to a new poll of Miami-Dade Hispanics that reveals deep divisions within a community traditionally viewed as staunchly Republican.

The poll, commissioned by a Democratic group that is targeting Hispanic voters, shows Kerry with a 58-32 percent advantage among Cubans born in the United States, suggesting that the Massachusetts senator has an opportunity to siphon potentially critical support from Bush.

But the poll, to be released today, shows Bush crushing Kerry among the largest -- and perhaps most politically active and vocal -- group of Cuban-American voters: those who arrived before the 1980 Mariel boatlift. Those voters -- who make up about two-thirds of all Cuban-American registered voters in Miami-Dade, according to the survey -- back the Republican incumbent overwhelmingly, 89 to 8 percent, with just 3 percent undecided.

Among all Cuban-American voters, Bush leads Kerry 69 to 21 percent, with 10 percent undecided -- a massive lead, but a decline from 2000 when more than eight of 10 Cuban Americans helped Bush narrowly defeat Al Gore in Florida and win the White House.

Kerry leads Bush 40 to 29 percent among Cubans who arrived in the United States after 1980, with 31 percent undecided.

Among all Hispanic voters in Miami-Dade, Bush leads Kerry 60 to 29 percent, with 11 percent undecided.

The New Democrat Network, which today will launch a Hispanic voter project in Miami -- billing it as the party's first aggressive outreach effort in Republican-rich Hispanic South Florida in 30 years -- suggested the poll points to vulnerability for a president who won the state in 2000 by just 537 votes.

''This isn't enough in any way to lead one to imagine we'll win the Hispanic vote, but there's definitely an opportunity to put a dent in the Republican column,'' said Democratic pollster Sergio Bendixen, who is consulting for the Washington, D.C.-based group and conducted the survey. ``For the first time in a generation, people are actually talking about which way they may go.''

The poll of 800 likely Hispanic voters was conducted June 1-5 for the group by Bendixen's polling firm, which has long surveyed Hispanics in South Florida. Conducted primarily in Spanish, the poll has a margin of error of three percentage points, though smaller subgroups have a greater margin of error, ranging from five percentage points among the subgroup of all Cubans to nine percentage points among Cubans born in the United States.

Recent polls show Florida too close to call and the survey underscores what is increasingly becoming a battle of the 2004 election: the quest to peel away Cuban Americans, a key GOP voting bloc in the state that decided the 2000 race.

Sensing vulnerabilities among that base, Bush has moved in recent months to shore up support, rolling out plans to harden the economic sanctions against the Cuban government, including restricting gifts and family visits to Cuba.

The hard-line approach has endeared him to some exile groups, but has triggered a backlash from some moderate Cuban Americans, who support the U.S. trade embargo but want to be able to travel and support relatives in Cuba.

Kerry has sought to exploit that divide, telling The Herald on Friday that Bush's policy will only hurt ordinary Cubans and suggesting he would encourage more travel to Cuba, lift the gift cap and pursue greater international condemnation of Fidel Castro.

Ninoska Pérez-Castellón, a spokeswoman for the Cuban Liberty Council, which has applauded Bush's recent crackdown on remittances and travel to the island, said the poll doesn't reflect what will happen in November.

''I don't care how many polls the Kerry people do, how they dress it up,'' she said. ``The bottom line is none of this is going to blind us when it comes to voting.''

Maria Cardona, director of the New Democrat Network's's Hispanic Project, said it was committed to fighting for votes among Hispanics in Miami -- whatever the poll revealed.

``If our Hispanic project was going to be true to its goals, there was no way we could ignore Miami.''