Dick Cheney kept a resignation letter in a safe the whole time he was Vice President.

He reveals this in his memoirs, which are coming out next Tuesday. Only Cheney, President Bush, and one staffer knew of the letter's existence.

Cheney's reason:

"[T]here is no mechanism for getting rid of a vice president who can’t function."

He also makes this tantalizing statement about his book:

"I didn’t set out to embarrass the president or not embarrass the president."