In United States politics, an October surprise is a news event that may influence the outcome of an upcoming November election (particularly one for the presidency), whether deliberately planned or spontaneously occurring. Because the date for national elections (as well as many state and local elections) is in early November (with in-person early voting, absentee, and mail-in voting also generally taking place in most states during the period of late-September to early November), events that take place in October have greater potential to influence the decisions of prospective voters and allow less time to take remedial action; thus, relatively last-minute news stories could either change the course of an election or reinforce the inevitable. Common political events that have been referred to as an October surprise include political scandals, sudden international crises, criminal investigations, health issues involving a candidate, news leaks, natural disasters, and major policy announcements.

The term "October surprise" was coined by William Casey when he served as campaign manager of Ronald Reagan's 1980 presidential campaign; however, there were October election-upending events that predated the coining of the term.

Prior to 1980 19th century In mid-October 1840, shortly before the 1840 presidential election, federal prosecutors announced plans to charge top Whig Party officials with "most stupendous and atrocious fraud" for paying Pennsylvanians to cross state lines and vote for Whig candidates in New York during the 1838 elections. Whig candidate William Henry Harrison later won the election.

In 1844, an abolitionist newspaper published an article, purportedly based on a book titled Roorback's Tour Through the Southern and Western States in the Year 1836, implying that James K. Polk (who later won the election) had his slaves branded.Mark E. Byrnes, James K. Polk: A Biographical Companion (ABC-CLIO: New York, 2001), pp.182-3 For some decades afterward, a practice similar to the modern "October surprise", in which the occurrence turned out to be untrue, was called "roorbacking" or "roorbaching".

On October 20, 1880, shortly before the 1880 presidential election, a forged letter was published purportedly written by James A. Garfield voicing support for Chinese immigration to the United States. At the time, most white Americans opposed Chinese immigration and both presidential candidates were in favor of immigration restrictions. Garfield later won the election.

In the week leading up to the 1884 presidential election, Republican nominee James G. Blaine attended a meeting in which Presbyterian preacher Samuel D. Burchard claimed that the Democrats were the party of "Rum, Romanism, and Rebellion". Blaine's failure to object to Burchard's message cost him support from anti-prohibitionists, Roman Catholic immigrants, and southerners, playing a role in his narrow loss to Democratic candidate Grover Cleveland.

Two weeks before the 1888 presidential election, the Republicans published a letter by Lionel Sackville-West, the British ambassador to the United States. In the letter, Sackville-West suggested that Democratic presidential candidate Grover Cleveland was preferred as president from the British point of view. The letter had a galvanizing effect on Irish-American voters exactly comparable to the "Rum, Romanism, and Rebellion" blunder of the previous presidential electionCharles W. Calhoun, Minority Victory: Gilded Age Politics and the Front Porch Campaign of 1888 (2008). by trumpeting Great Britain's support for the Democrats. That drove Irish-American voters into the Republican fold, and Cleveland lost the presidency to Republican candidate Benjamin Harrison.

20th century In the weeks leading up to the 1920 presidential election, rumors circulated that Warren G. Harding was of African-American descent. Harding's campaign feared that the rumor would affect his popularity amongst white southerners and sought to prove Harding's whiteness. Harding later won the election.

Less than a month before the 1940 presidential election, President Roosevelt's press secretary Stephen Early kneed a black police officer in the groin outside Madison Square Garden. Roosevelt had already been facing skepticism from black voters because of his failure to desegregate the military. Roosevelt responded days before the election by appointing the nation's first black general, Benjamin O. Davis Sr., and announcing the creation of the Tuskegee Airmen. He later won the election.

The Suez Crisis and Hungarian Revolution have both been described as October surprises during the 1956 presidential election. Republican Dwight D. Eisenhower was reelected in the 1956 presidential election.

On October 7, 1964, just under a month before the 1964 presidential election, one of President Johnson's top aides, Walter Jenkins, was arrested for disorderly conduct with another man (homosexual activity) at the Washington D.C. YMCA, a place described by the Toledo Blade as "so notorious a gathering place of homosexuals that the District police had long since staked it out with peepholes for surveillance". Johnson later won the election.

During the 1968 presidential election, Hubert Humphrey—who was rising sharply in the polls due to the collapse of the George Wallace vote—began to distance himself publicly from the Johnson administration on the Vietnam War, calling for a bombing halt. The key turning point for Humphrey's campaign came when President Johnson officially announced a bombing halt, and even a possible peace deal, the weekend before the election. The "Halloween Peace" gave Humphrey's campaign a badly needed boost. In addition, Senator Eugene McCarthy finally endorsed Humphrey in late October after previously refusing to do so, and by election day the polls were reporting a dead heat.Theodore H. White, The Making of the President, 1968 (1970) However, Nixon won the election in a close race.

During the 1972 presidential election between the Republican incumbent Richard Nixon and the Democratic nominee George McGovern, the United States was in the fourth year of negotiations to end the lengthy and domestically divisive Vietnam War. On October 26, 1972, twelve days before the election on November 7, the United States' chief negotiator and presidential National Security Advisor Henry Kissinger appeared at a press conference held at the White House and announced "We believe that peace is at hand."Kissinger 2003:591 Nixon, despite having vowed to end the war during his presidential election campaign four years earlier, had failed to cease hostilities but had withdrawn all American ground combat units and most other American military personnel. While Nixon was nevertheless already widely considered to be assured of re-election, Kissinger's "peace is at hand" declaration increased Nixon's already high standing with the electorate: in the event, Nixon defeated McGovern in every state except Massachusetts and won by 23.2 points in the nationwide popular vote, which was the largest margin since 1936. Remaining U.S. military personnel were withdrawn in 1973, but U.S. involvement in Vietnam continued until 1975.

1980 presidential election

Origin of term In the 1980 presidential election, Republican challenger Ronald Reagan feared that a last-minute deal to release American hostages held in Iran might earn incumbent Jimmy Carter enough votes to win re-election. As it happened, in the days prior to the election, press coverage was consumed with the Iranian government's decision—and Carter's simultaneous announcement—that the hostages would not be released until after the election.

William Casey, the manager of the Reagan campaign, was the first person to mention the idea of an "October surprise" to the press. On the morning of July 17, he told the press at the Republican convention that he was concerned that Carter would use the advantage of incumbency to spring an event that would benefit him politically. Casey mentioned that Carter had done this during the Wisconsin primary—in reference to Carter's announcement on election morning that he had "good news" concerning the hostages. Casey mentioned to the press that he was setting up an "intelligence operation" to monitor Carter's political activities to keep abreast of such a possibility.

The intelligence operation the Reagan campaign set up was extensive. It used military contacts at key air force bases to keep track of military flight movement which could be used to gauge government action concerning the hostages. The operation had also compiled a list of the embargoed military equipment that the U.S. government had of the Iranians that Carter could use to barter in exchange for the release of the hostages. To keep abreast of international information concerning the hostages, the Reagan campaign tapped former Secretary of State Henry Kissinger and his extensive network of international contacts.

The Reagan campaign's ominous warnings of a possible October surprise to the press was done for strategic reasons. It was intended to prepare the voters, so that if some good October news happened, the voters would look at the event as a political ploy by the Carter campaign to win the election. Personal papers left by Joseph V. Reed Jr. indicate that the "team" around David Rockefeller, the chairman of Chase Bank, "collaborated closely with the Reagan campaign in its efforts to pre-empt and discourage what it derisively labeled an 'October surprise'—a pre-election release of the American hostages, the papers show. The Chase team helped the Reagan campaign gather and spread rumors about possible payoffs to win the release, a propaganda effort that Carter administration officials have said impeded talks to free the captives." Rockefeller, a lifelong Republican, assisted the Reagan campaign because he had a negative view on Carter's dovish foreign policy, and also because Chase Bank's balance sheet held $360 million (equivalent to $ in ) in loans to Iran and more than $500 million (equivalent to $ in ) in frozen Iranian deposits.

Jack Anderson wrote an article in The Washington Post in the fall of 1980 about a possible October surprise, in which he alleged that the Carter administration was preparing a major military operation in Iran for rescuing U.S. hostages in order to help him get re-elected. Subsequent allegations surfaced against Reagan alleging that his team had actively impeded the hostage release.

Secret deal accusation After the release of the hostages on January 20, 1981, minutes after Reagan's inauguration, some charged that the Reagan campaign had made a secret deal with the Iranian government whereby the Iranians would hold the hostages until after Reagan was elected and inaugurated. Gary Sick, member of the U.S. National Security Council under Presidents Ford and Carter (before being relieved of his duties weeks into Reagan's term), made the accusation in a New York Times editorial reprinted in in the run-up to the 1992 election. The initial bipartisan response from Congress was skeptical: House Democrats refused to authorize an inquiry, and Senate Republicans denied a $600,000 appropriation for a probe. Eight former hostages also sent an open letter demanding an inquiry in 1991. In subsequent Congressional testimony, Sick said that the popular media had distorted and misrepresented the accusers, reducing them to "gross generalizations" and "generic conspiracy theorists". Sick penned a book on the subject and sold the film rights to it for a reported $300,000. His sources and thesis were contested by a number of commentators on both sides of the aisle.