Before the
1972 election, Muskie was viewed as a frontrunner for the Democratic Presidential nomination. The nation was at war in
Vietnam and President
Richard Nixon's war policies (and foreign policy, more generally) promised to be a major issue in the campaign.
The 1972
Iowa caucuses, however, significantly altered the race for the Presidential nomination. Left-wing
dark horse candidate, South Dakota Senator
George McGovern, made a strong showing in the caucuses, giving his campaign national attention. Although Muskie won the Iowa caucuses, McGovern's campaign left Iowa with momentum. Muskie himself had never participated in a primary election campaign, and it is possible that this led to the downfall of his campaign. Although Muskie went on to win the
New Hampshire primary, the victory was only by a small margin, and his campaign faltered.
The collapse of Muskie's momentum early in the 1972 campaign is also attributed to his response to campaign attacks. Prior to the
New Hampshire primary, the so-called
Canuck Letter was published in the
Manchester Union-Leader. The letter claimed that Muskie had made disparaging remarks about
French-Canadians – a remark likely to injure Muskie's support among the French-Canadian population in northern New England. Subsequently, the paper published an attack on the character of Muskie's wife
Jane, reporting that she drank and used off-color language during the campaign. Muskie made an emotional defense of his wife in a speech outside the newspaper's offices during a snowstorm. Though Muskie later stated that what had appeared to the press as tears were actually melted snowflakes, the press reports that Muskie broke down and cried shattered the candidate's image as calm and reasoned.
Evidence later came to light during the
Watergate scandal investigation that, during the 1972 presidential campaign the
Nixon campaign committee maintained a "dirty tricks" unit focused on discrediting Nixon's strongest challengers (see
Ratfucking). FBI investigators revealed that the Canuck Letter was a forged document as part of the dirty-tricks campaign against Democrats orchestrated by the Nixon campaign.