If he dies in office, then Dick Cheney becomes President.
When Bush was president, if he died, the vice president, Dick Cheney will become president (or Dan Quayle if speaking of George Bush Sr.) If Bush dies now, Barack Obama will remain president.
george
At the time of his presidency yes, but no longer since he is no longer president.
The vice president
The Vice President
The vice-president
the vice president.
If both die then the Speaker of the House becomes president
The vice-president becomes the president.
If Obama dies in office, his vice President, Joe Biden, becomes the next President.
President pro tempore of the Senate becomes President.
The Vice President of America.