President Gerald Ford announcing he would pardon Richard Nixon, September 8th, 1974.
Ford's presidency was a short one -- barely two years. Many, including Ford himself, blamed his pardon of Nixon for the brief presidency and his losing out in the 1976 election to Jimmy Carter.
Ford insisted he pardoned Nixon because the two were friends and Nixon had simply made a mistake (deceiving the country and sanctioning an illegal break-in), but the country disagreed with his friendly gesture. Critics called it a "corrupt bargain", a phrase first made famous in the 1824 election between John Quincy Adams and Andrew Jackson.
Whether Ford was just trying to help a buddy out, or it was indeed a corrupt bargain, the country was not happy with his decision and punished him two years later in the next election. After much political turmoil and many lies, a failed war in Vietnam, dissatisfaction with the previous two presidents Johnson and Nixon, both of whom deceived the country in their owns ways, the last thing the country wanted was their new president to take the side of the old system they disdained.
So, instead, at their next opportunity, the country gave their votes to a 'political outsider': Jimmy Carter.