US president Barack Obama is taking his re-election campaign into the South on Labour Day, where he will offer a presence and promises of help to those flooded out recently by Hurricane Isaac.

Hurricane Isaac sidestepped New Orleans, sending the worst of its howling wind and heavy rain into a cluster of rural fishing villages with few defences against the slow-moving storm that could bring days of unending rain.

Tropical Storm Bill pounded the Gulf Coast today, spinning off a tornado that injured four people and left nearly 200,000 homes and businesses without power.