Florida is bracing for Tropical Storm Isaac, due to make landfall Sunday in the Florida Keys just off the U.S. mainland

at or near hurricane strength.

The U.S. National Hurricane Center warns isolated tornadoes are also possible Sunday over portions of the Keys and central and southern Florida.

Isaac has maximum sustained winds near 95 kilometers per hour with higher gusts.

Offshore drilling operators in the Gulf of Mexico have begun shutting down their facilities, hoping to avoid damage from the storm.

Isaac battered eastern Cuba Saturday, after killing at least three people in Haiti, which is still recovering from a devastating 2010 earthquake. There were no reports of fatalities in Cuba.

The threat of the storm has caused the U.S. Republican Party to postpone the start of most events at its national convention in Tampa, Florida from Monday to Tuesday afternoon.

Protesters who have set up camp in Tampa, dubbed “Romneyville,” near the site of the Republican convention will likely need to abandon their outdoor accommodations.