"In your guts, you know he's nuts" was a campaign slogan used against which U.S. presidential candidate?

As an important part of the history of U.S. political campaigning, a slogan used by Barry Goldwater in the 1964 U.S. Presidential race was "In your heart you know he's right". Goldwater, as the head Republican politician, was then very well-known for using and believing hardline small government anti-communist rhetoric. He loved to point to and defend his strong "extremism"; he did this with total commitment in his acceptance speech for the 1964 GOP presidential nomination.

Goldwater's campaign team at the start attempted to appeal to the gut instincts of certain groups of American voters with the slogan: "In your heart, you know he's right". The response of his Democrat opponent, Lyndon Baines Johnson, was devastating. The Democratic reply in clever campaign ads and posters was "In your guts, you know he's nuts". This is a quote that was run at every opportunity during the entire campaign period of the Democratic party. It was used at all social levels within every part of America.

Johnson won by a landslide, taking 61% of the popular vote to Goldwater's 38%. Goldwater won in just six states.