GOP officials were in round-the-clock meetings and tracking the path of the storm, trying to determine how to complete the official business of nominating McCain while also being sensitive to the thousands of people fleeing the Gulf Coast - more than 1,000 miles down the Mississippi from St. Paul.
Cancellations by major speakers came as Republicans scrambled to change the tone - and perhaps the length - of their national convention, even as delegates streamed into town.
McCain, the Republicans' nominee-in-waiting, tore up his campaign schedule to visit Jackson, Miss., with his running mate, Sarah Palin, to get briefings on the approaching storm. He was invited by Mississippi Gov. Haley Barbour.
Bush and Cheney, both of whom were to have spoken Monday night, weren't coming, the White House said Sunday, citing the hurricane.
California Gov. Arnold Schwarzenegger backed out in an unrelated budget dispute with California legislators.
All three were to address the convention on Monday, it's opening day.
McCain said in an interview taped on Saturday and aired Sunday on Fox News Sunday that he had conferred by phone with Barbour as well as Govs. Bobby Jindal of Louisiana, Bob Riley of Alabama and Charlie Crist of Florida. Crist wasn't coming to St. Paul, and there others seemed unlikely as well.
"I've been talking to all of them," McCain said. He said the approaching storm had already put a cloud over the convention.
"It just wouldn't be appropriate to have a festive occasion while a near tragedy or a terrible challenge is presented in the form of a natural disaster," McCain said. Still, he said, "I think that we are far, far better prepared than we were the last time."
The Bush White House and Republicans in general are still shadowed by criticism of their handling of relief efforts in after Hurricane Katrina, which devastated New Orleans and parts of the Mississippi Gulf Coast three years ago. Party leaders fear that televised scenes of celebrations and partying at the convention could subject them to similar criticism now.