US Republican Party officials have delayed the start of their national convention until Tuesday because Tropical Storm Isaac is barreling toward the Florida coast.
"Due to the severe weather reports for the Tampa Bay area, the Republican National Convention will convene on Monday August 27 and immediately recess until Tuesday afternoon, August 28," party chairman Reince Priebus said.
US weather forecasters warned that Isaac, which has already battered Haiti and Cuba, could be at or near hurricane strength when it brushes the Florida Keys archipelago and the southern Florida peninsula on Sunday.
The convention, at which former Massachusetts governor Mitt Romney is to be nominated as the party's challenger to take on President Barack Obama in the November presidential election, is to be held in the coastal city of Tampa.
But Priebus insisted that, after consulting with weather experts and local officials, he remained "optimistic that we will begin an exciting, robust convention".
Republican officials expect 50,000 people to descend on Tampa for speeches, parties and the formal nomination and the convention's president Bill Harris said the safety of all participants was the "foremost concern" of organisers.
Tampa mayor Bob Buckhorn, a Democrat, had 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 that this would be followed by sunny skies.
"There may be wet shoes, but every day after Monday ought to be fine," Buckhorn told Fox News before the Republicans announced the one-day delay to the start of the convention proper.