The US Republican Party has effectively postponed the start of its national convention until Tuesday afternoon, due to severe weather expected from Tropical Storm Isaac.

Reince Priebus, the chairman of the party, said that the convention in Tampa would convene briefly on Monday, and then immediately recess until Tuesday afternoon, once the bulk of the storm is expected to have passed.

Priebus said that the party made the decision after consulting with Florida Governor Rick Scott and federal and local emergency officials.

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Although Mitt Romney, the party's nominee-in-waiting, is not addressing the convention until Thursday night, delegates had been scheduled to take the traditional roll call making him the nominee on the opening day.

This is the second Republican convention in a row to be delayed due to severe weather. The 2008 convention in Minnesota was delayed by a day because of a hurricane.

Al Jazeera's James Brownsell, reporting from Tampa, said that the storm was expected to pick up strength as it entered the Gulf of Mexico, possibly becoming a category one hurricane.

"Isaac is not expected to hit Tampa, but it could hit land anywhere along the coast, from southern Florida to New Orleans," he reported.

"Local politicians - including Florida governor Rick Scott - said, before the party's announcement that they would be staying away from the convention in order to be able to concentrate on potential disaster management, should it be necessary in the next few days."

Tropical Storm Isaac on Saturday dumped torrential rain on Haiti, killing at least four people and flattened tent camps housing survivors of the devastating 2010 earthquake there, before skirting eastern Cuba.