Tropical Storm Isaac lashed southern Florida yesterday and was expected to become a hurricane after forcing a one-day delay to the main events of the United States Republican convention.

With winds reaching 100 kilometres per hour, the storm brought rain and choppy seas to the Florida Keys after battering Haiti and sweeping across Cuba late on Saturday, the Miami-based 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.

According to the adjusted plan, the gathering will nominally open today and then immediately adjourn to reconvene tomorrow, when the weather is expected to clear up.

Early yesterday, 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 advisory yesterday, the NHC said Isaac was expected to be at or near hurricane strength as it passes over the Keys and predicted “hurricane conditions” there and in southwest Florida.

After sweeping across the string of islands off Florida’s southern coast, the storm is on track to churn through the Gulf and make landfall on Wednesday in Louisiana or Mississippi. 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 presidential election.

Republican National Committee Chairman Reince Priebus told CNN the decision was motivated by concern for delegates travelling in buses over long bridges and the difficulty of erecting tents to shelter security lines at venue entrances.

He insisted that the show would go on, saying: “We’re 100 per cent full steam ahead on Tuesday.”

Thousands of convention delegates are staying in hotels along a coastal barrier island, which is likely to bear the brunt of the storm.

Vice President Joe Biden canceled a trip to Tampa and other Florida cities due to the storm.

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