TULSA, Okla. -- Problems with cabin pressure forced a plane carrying Laura Bush, Lynne Cheney and Cindy McCain to make an unscheduled stop here Monday, a spokesman for George W. Bush's presidential campaign said.

The women were en route to Wisconsin for "W Stands for Women" rallies as part of Bush's campaign.

"The oxygen masks dropped down, which was a little bit of a sign," Laura Bush said. "We really weren't frightened at all. We used the oxygen a little bit at one point. We all decided we thought it was psychological that we were having trouble breathing, but we weren't."

"Everyone is fine," spokesman Bob Hopkins said.

The plane landed in Tulsa about an hour after it departed Austin, Texas. Hopkins said problems arose with the cabin air pressure controller.

The wives of Bush, vice presidential nominee Dick Cheney and Arizona Sen. John McCain spent about three hours in the lounge at Mercury Air at Tulsa International Airport while a 727 was brought in to complete the trip. Everyone was in good spirits and laughing as they waited.

Condoleezza Rice, Bush's national security adviser, also was on board.