In a videotaped message, Obama says the queen is a “living witness” to the power of the alliance between the U.S. and Britain and a chief source of its resilience.
Obama says that while many U.S. presidents and British prime ministers have come and gone, the queen's reign has endured. The president says he hopes the queen remains on the throne for many years to come.
The president and Michelle Obama were guests at Buckingham Palace last year when the queen hosted them for an official state visit, a rare honor for a U.S. president.