Washington - Hurricane Gustav Sunday played havoc with Republican Party plans to nominate their presidential candidate as US President George W Bush dropped a speech scheduled for Monday to fly to Texas.

As Gustav bore down on New Orleans with expected landfall in the early morning hours Monday, Senator John McCain, 72, said most Republican convention activities in St Paul, Minnesota would be suspended on Monday.

McCain is to be nominated at the convention, which runs from Monday to Thursday.

McCain said in broadcast remarks that Republicans would "take off our Republican hats and put on our America hats" in the face of the approaching natural disaster.

McCain's campaign manager, Rick Davis, said that Republican delegates would meet briefly Monday to do the minimal requirements of the convention - adoption of rules and the party platform, and validation of delegates' credentials.

The meeting would "refrain from any political rhetoric that would be traditional on the opening day of the convention," Davis said in broadcast remarks.

McCain and Davis said Republicans would be urged to raise money for storm victims. Davis said the storm's course would determine on a day-to-day basis whether the full convention's programme would be resumed on Tuesday.

Instead of flying to St Paul, Bush said he would travel to Austin, Texas "to visit with the emergency oeprations center" and to San Antonio where relief materials are being gathered for Texas and Louisiana.

Vice President Dick Cheney and First Lady Laura Bush were also to speak Monday night, but those plans were also cancelled.

A million people were fleeing their homes in New Orleans on Sunday as Gustav bore down on the city, hours after inflicting "considerable damage" in western Cuba.

New Orleans Mayor Ray Nagin bluntly told citizens: "You need to be scared. You need to be concerned, and you need to get your butts moving out of New Orleans right now. This is the storm of the century."

Gustav strengthened to a dangerous category 4 hurricane late on Saturday but dropped back to category 3 by Sunday afternoon, on the 1-to-5 Saffir-Simpson Hurricane Scale. The storm was expected to make US landfall on Monday by noontime local time (1500 GMT), possibly back up to Category 4 strength.

In 2005, Hurricane Katrina wreaked devastation on New Orleans with a flood surge that left tens of thousands stranded for days without food and water while the federal government failed to act.

The catastrophe of delayed intervention was among the blackest marks dealt the Bush administration during its eight years in office.