WASHINGTON – Ten days before he died, John F. Kennedy met in the White House for several hours with his political advisers. The 1964 campaign was taking shape -- Barry Goldwater and Nelson Rockefeller were the leading Republican rivals -- and the president was worrying about what his party had to offer to average voters."What is it that we can do to make them decide that they want to vote for us, Democrats and Kennedy?" the president asked. "We hope we have to sell them prosperity, but for the average guy the prosperity is nil.