St Paul, Minnesota - US First Lady Laura Bush gave a first jolt of energy to Republican delegates starved of star power on the first day of the centre-right party's presidential nominating convention.

She has remained a popular national figure across party lines, even with approval ratings for her husband, President George W Bush, languishing around 30 per cent.

The president and Vice President Dick Cheney were due to headline the first night of the four-day convention before Hurricane Gustav's landfall on the Gulf Coast led Republicans to scuttle Monday evening's speeches.

The cancellations left the first lady and Cindy McCain, wife of Republican standardbearer John McCain, as the best-known participants in Monday's brief programme.

The 2,200 delegates rose in a standing ovation for Laura Bush in an explosion of camera flashes. As the other 49 states cheered, the delegation from her home state of Texas - all in blue denim shirts - waved their straw cowboy hats.

Tammy Sturm, a delegate from Houston, called Bush "wonderful, ... a warm, cozy, Southern, Texas mom."

"She's home-made, country, all the way," said Sturm, a mother of three who works for a biomedical laboratory.

Bush introduced greetings by video from the all-Republican governors of the five states on the Gulf of Mexico currently bracing for Hurricane Gustav: Florida, Alabama, Mississippi, Louisiana and Texas.

Cindy McCain then joined Bush on stage, receiving a similarly rousing welcome. Both women issued appeals for the party's supporters and people across the country to make donations and volunteer time to help evacuees from the hurricane zone and support the eventual cleanup and rebuilding.

"I would ask that each one of us commit to join together to aid those in need as quickly as possible," Cindy McCain said.

Hollywood actor Jon Voight, a McCain supporter, said later on the floor of the convention that he was "very impressed with Cindy McCain." (dpa)