A radio problem on the Marine One helicopter prevented it from taking off from the White House lawn Wednesday, forcing President Bush to wait for a motorcade to take him to nearby Andrews Air Force Base.

Bush and his senior advisers had boarded the helicopter and it revved up in preparation for takeoff, but after about a minute its engines were shut down. Bush got off smiling.

"We had an issue with the helicopter," the president said. "Everyone's safe."

Bush walked off to shake hands with visitors who came to see the takeoff. White House Deputy Chief of Staff Joe Hagin said the helicopter's radio had failed. "They couldn't talk to anyone," he said.

A motorcade was being assembled to take Bush to the air force base to begin his flight to Tuskegee, Ala.