Tropical Storm Isaac lashed southern Florida Sunday and was expected to become a hurricane, forcing a one-day delay of the US Republican convention, after killing seven people in Haiti, AFP reports.
With winds reaching 50 miles (85 kilometers) per hour, the storm brought heavy rain and choppy seas to the Florida Keys after battering Haiti and sweeping across Cuba late Saturday, the US National Hurricane Center said.
A hurricane warning was in effect for the Florida Keys and parts of the state's southwest coast, and the Republican Party announced that severe weather warnings had postponed the start of its four-day gathering in Tampa.
The gathering is now set to nominally open Monday and then immediately adjourn to reconvene on Tuesday, when the weather is expected to clear up.
Early Sunday, the eye of the storm was around 80 miles southeast of Key West, Florida, and it was moving northwest at 18 miles per hour, with forecasts suggesting it would strengthen over the next 48 hours, the NHC said.
In its 2:00 pm (1800 GMT) advisory, the Miami-based NHC said "hurricane" conditions" were possible in the Keys and southern Florida.
It predicted Isaac would become a hurricane as it moves back into the Gulf on a path that would have it make landfall Wednesday on the southern US coast.
Tens of thousands of Republicans will be in Tampa for speeches, parties and the formal nomination of former Massachusetts governor Mitt Romney as the candidate to take on President Barack Obama in the November 6 election.
Officials said they did not fear a direct hit on the city but had acted out of concern that high winds, rain and possible coastal flooding could make travel dangerous, particularly for large buses packed with delegates.
Republican National Committee Chairman Reince Priebus told CNN the decision was motivated by concern for buses traveling over long bridges and the difficulty of erecting tents to shelter security lines at venue entrances.
He insisted, however, that the show would go on, saying: "We're 100 percent full steam ahead on Tuesday."
Thousands of convention delegates are to stay in hotels along a coastal barrier island, which is likely to bear the brunt of the storm, and a decision was to be made on Sunday over whether to move them to higher ground.
Tampa Mayor Bob Buckhorn, a Democrat, sought to calm jitters about the weather, saying the storm might bring heavy rain to Tampa on the first of the four-day convention but insisting that "Tuesday is going to be fine."
Governor Rick Scott told CNN his state was prepared for any scenario.
"We're a state that knows how to do hurricanes. We don't like them, but we know how to do them. We do hurricanes well," he told CNN.
The White House said Obama had been briefed on storm preparations and had spoken with Scott, offering federal support for "efforts to ensure the safety of those visiting the state for the Republican National Convention."
Vice President Joe Biden canceled a trip to Tampa and other Florida cities because of the approaching storm, Obama's Democratic campaign said.
And in the Gulf of Mexico, BP evacuated its Thunder Horse platform, the world's largest offshore production and drilling facility.
Isaac was near hurricane strength early Saturday when the eye of the storm passed over Haiti, where hundreds of thousands of people are still living in squalid, makeshift camps following a catastrophic 2010 earthquake.
An eight-year-old Haitian girl died when a wall collapsed at her home and a 51-year-old woman died when her roof collapsed, according to officials, who later said five other people had also died in the storm.
More than 5,000 families had been evacuated to temporary shelters ahead of Isaac as aid groups provided clean water and hygiene kits to try to limit the risk of contaminated water and the spread of disease.