US President Barack Obama will tour storm damage and visit victims of Hurricane Isaac on Monday, the White House said Friday, as Republican rival Mitt Romney headed for the disaster zone.

White House spokesman Jay Carney said top officials had assessed that Monday was the most appropriate day to visit Louisiana as they were keen to ensure the huge presidential security operation did not detract from relief efforts.

Carney told reporters on Air Force One that Obama would meet officials dealing with the aftermath of Isaac, which tore ashore in New Orleans exactly seven years after killer Hurricane Katrina.

But he sidestepped questions inviting him to judge whether it was appropriate for Romney, who has no official role in dealing with the storm, to go to Louisiana hours after accepting his party's presidential nomination.

"It is always important to draw attention to the fact that individuals and families and business owners are profoundly affected by the storm," Carney said.

Romney is expected to meet Louisiana Governor Bobby Jindal and first responders in the town of LaFitte later Friday.

Romney's team announced the last-minute change early in the day in Lakeland, Florida, where the candidate and his running mate Paul Ryan had scheduled a rally.

In a press call, the White House underscored that the decision to travel to the region on Monday was made before Romney announced his plans.

Three days after Isaac made landfall, authorities in Mississippi and Louisiana urged residents to seek shelter amid fears a dam, under pressure from elevated river levels, could fail.

Mindful of the high political price former president George W. Bush's administration paid for the botched handling of Katrina, Obama made a forceful public effort to show he was closely managing Isaac.

He warned people to heed warnings from local officials, in an apparent effort to show Americans that the vast machinery of the US government, which Republicans decry, could be wielded for everyone's benefit.