This is an excerpt of an article I wrote in 2007:
The “secret plan” myth began when Nixon made a campaign stop in Hampton, NH during the 1968 primary campaign. He said that if elected president, his administration would “end the war and bring peace to the Pacific.”
Somehow, this broad and rather vague promise morphed into a “secret plan” claim. In 2002m Nixon speechwriter Ray Price said that a wire service reporter mistakenly called Nixon’s promise a plan and New York governor Nelson Rockefeller, also vying for the Republican nomination for president, added the word “secret,” The Democrats quickly made the “secret plan” an issue and demanded Nixon make it public. Nixon fired back, saying he had no “gimmicks or secret plans.”
Nonetheless, the Democrats kept referring to the “secret plan.” In 1972, George McGovern, Nixon’s Democratic rival for the White House, brought it up frequently, and in 1980, President Carter referred to it during his re-election campaign. The myth has continued into this century with journalists occasionally referring to Nixon’s “secret plan” to settle the war.