Officials in earthquake-ravaged Haiti are assessing damage from Tropical Storm Isaac, which moved over the impoverished Caribbean island early Saturday.

Relief workers are concerned about hundreds of thousands of people who are still living in tent camps and other makeshift structures, more than two years after a catastrophic earthquake caused enormous damage in and around Haiti's capital .

There also are fears that the storm's heavy rains could result in mudslides and flooding.

The U.S. National Hurricane Center says the tropical storm is moving northwest at about 23 kilometers per hour, with maximum sustained winds of 97 kilometers per hour. Isaac is headed toward southern Cuba and could reach hurricane strength before possibly hitting the the southern tip of Florida by Monday.

Organizers of next week's U.S. Republican National Convention in Tampa, Florida, are keeping a watchful eye on Isaac.

Forecasters say it is not yet clear what impact the storm might have on the four-day political gala on Florida's Gulf coast. Tampa is more than 300 kilometers north of Miami, Florida's southernmost major city.