ST. PAUL, Minn. -- With the Republican National Convention set to open Monday in St. Paul, the threat posed by Hurricane Gustav has already prevented prominent GOP officials from attending and has John McCain on edge about whether the event should be postponed.

Convention planners insist the week-long celebration is going forward as scheduled.

But the presumptive GOP nominee told FOX News, in an interview to air on "FOX News Sunday," that holding the convention while Gulf Coast residents suffer would be insensitive.

"I'm afraid ... that we may have to look at that situation and we'll try to monitor it," McCain said. "But you know 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. So we're monitoring it from day to day and I'm saying a few prayers too."

McCain and his running mate Sarah Palin will travel to Mississippi on Sunday to check on people getting prepared for Gustav. The two are expected to receive a briefing at the Mississippi Emergency Management Agency.

The possibility of putting the convention on pause has been on the minds of party leaders over the past several days, as residents of New Orleans and other cities along the Gulf Coast begin to evacuate, girding for what some fear could be a storm that carries the impact of Hurricane Katrina three years ago. Gustav strengthened to a Category 4 hurricane Saturday. The storm crossed Cuba's western tip before moving into the Gulf of Mexico and could reach the U.S. by late Monday or early Tuesday.

The convention has already been impacted by the approaching storm.

Texas Gov. Rick Perry, set to speak Monday, has canceled his plans to attend, a spokeswoman told FOXNews.com.

Louisiana Gov. Bobby Jindal has said he would skip the convention if the storm threatens the coast.

MyFox Gulf Coast reported Saturday that Mississippi Gov. Haley Barbour has canceled plans to attend due to the storm.

And Florida Gov. Charlie Crist, who is scheduled to speak Thursday, has so far postponed his trip to St. Paul because of the storm. Spokeswoman Erin Isaac told FOXNews.com Crist intended to travel to Minnesota Saturday but will probably wait until Tuesday. She said he is "monitoring" the storm and will adjust his schedule accordingly.

Up in the air is whether President Bush, set to address the convention Monday, will cancel his plans.

One of the reasons Bush was so criticized after Katrina was that he stuck to a schedule that took him from his ranch in Texas on a two-day trip to Arizona and California.

White House press secretary Dana Perino said staff are discussing a range of possibilities, including an address by satellite, in case Bush decides to cancel in favor of traveling to the region either before or after the storm. More was expected to be known Sunday.

"There is not a scheduling change to speak of tonight, but at the White House we are making contingency plans should the president decide against traveling to Minnesota for the RNC convention," she said.

Some also wonder if the hurricane could give Bush a ready excuse to skip, since McCain has been under fire from Democrats for being too cozy with the president, whose approval ratings are low.

Temple University professor Marc Lamont Hill said Republicans must be "praying for tornadoes." He predicted Bush would skip the event.

But House Republican Leader John Boehner told FOX News Friday that of course Republicans want Bush and Vice President Dick Cheney to attend.

Louisiana Reps. Rodney Alexander and Steve Scalise also plan to skip the convention.

The cancellations could leave somewhat of a void on the convention floor if the doors open at the Xcel Energy Center as scheduled.

Former Republican Governors Association Director Phil Musser said the storm has no doubt changed the tone of the upcoming convention, with the absence of prominent Republicans from the Gulf Coast.

"The chief executives are sort of the key stars in this party, so their presence will be missed here as we get ready to start this convention," he told FOX News.

But Michael DuHaime, McCain campaign political director, said the week-long affair will still have plenty of "stars" in attendance. He said "no decisions have been made" whether to postpone the event.

"Right now the plan is to go forward, but obviously this is a serious situation that we'll be watching," he said.

Others say postponing the convention is not likely, given the amount of preparation that goes into it.

Police have already cordoned off the streets surrounding the convention site, as reporters descend on the city and set up makeshift offices just outside the building.

"There are no plans for any postponement," said Mike Miller, director of operations for the Republican convention. "We plan to start when we were going to start and end when we were going to end."

Republican National Committee Deputy Chairman Frank Donatelli echoed Miller's prediction.

"I don't think (postponement) is a possibility," he said on a conference call with reporters. "To postpone a convention is much more difficult than you might think. ... I do believe there are other methods to deal with that potential situation so that we recognize and show the gravity of the situation and still do our business."

He said they would take "appropriate programmatic action" if necessary.

McCain asked voters to keep Gulf Coast residents in their prayers Saturday, as he and Palin, introduced Friday as his running mate, rallied more than 8,000 supporters at a minor league ballpark in Washington, Pa.

FOX News' Judson Berger, Mosheh Oinounou and Chad Pergram and The Associated Press contributed to this report.