CAPE CANAVERAL - Vice President Dick Cheney had seen a shuttle launch once before, but hoped Saturday that his three granddaughters would get their chance.

Storm clouds thwarted their hopes, however, for a roaring light show at liftoff. The booms would have to come at their next destination, NASCAR's Pepsi 400 in Daytona Beach.

"I was especially looking forward to having my grandchildren here," Cheney told reporters from atop the Operation Support Building, shortly after the launch controllers ordered a scrub.

"But we just got a tour of the Atlantis," he said. "At least we got to see that."

Earlier, Cheney had walked through the Orbiter Processing Facility at Kennedy Space Center, where he, his wife, Lynne, and their three granddaughters, Kate, 12, Elizabeth, 8, and Grace, 6, scoped the underbelly of shuttle Atlantis.

"There's actually 25,000 of these," Scott Thurston, a Kennedy Space Center manager, told them as they gazed up at the tiles underneath the shuttle.

Thurston then led Cheney and his family to the nose of the shuttle, where they peered up into the front wheel well of the extended landing gear.

Moments after the Discovery launch was called off, Cheney said he was "very impressed" by the tour of Kennedy Space Center and said of the space program: "It's a great program. It's important that we keep it going."

Other politicians on hand for the launch Saturday echoed similar support for the shuttle program, tempered with concerns about the consequences of another mishap.

"This is a critical launch," U.S. Rep. Dave Weldon, R-Indialantic, said. "We need this mission to go successfully for the future of our manned space flight program. . . . The support for NASA is very strong."

But that support could erode for the shuttle program, he said, should the space agency have another significant accident prompting further safety concerns.

Sen. Bill Nelson, D-Orlando, emphasized the importance of a smooth shuttle mission to ensure enough flights to finish the International Space Station by 2010 and to maintain and repair the Hubble Space Telescope.

"There's a lot riding on this launch because of the necessity of doing at least 16 flights to complete the space station," Nelson said. A 17th flight would include needed repairs to Hubble.