As the first state to cast a vote in the nominating process for U.S. presidential candidates, Iowa is famed for having an outsized influence on the contest for the White House.
But how often does the winner of the caucuses in the Midwestern state actually end up going on to become a party nominee or president?
Since 1976, there have been seven contested caucuses in the Republican Party. Of those contests, three winners have become the party's nominee.
Since 1972, there have been nine contested caucuses in the Democratic Party. Of those, the winner of the caucuses has gone on to be the Democratic nominee five times.
As those numbers show, Iowa picks the eventual nominee only about half the time. Since the 1970s, four candidates who went on to win the White House failed to win contested caucuses: Bill Clinton, George H.W. Bush, Ronald Reagan and Jimmy Carter.
DEMOCRATIC: Barack Obama, then a U.S. senator from Illinois, won Iowa in a pivotal victory for his insurgent campaign that won the presidency. Obama's victory pushed rival New York Senator Hillary Clinton into a third-place finish behind former vice presidential candidate John Edwards.
REPUBLICAN: Arkansas Governor Mike Huckabee won and the Republican Party's eventual nominee, Arizona Senator John McCain, came in fourth. Dating back to 1972, McCain is the only candidate to finish worse than third in the caucus and still win his party's nomination. Huckabee was outspent by Governor Mitt Romney, who finished second, but the former preacher was able to attract the state's many evangelical voters to his side.
DEMOCRATIC: Massachusetts Senator John Kerry won. He was his party's nominee but lost the presidency. Heading into the caucuses, Vermont Governor Howard Dean was deemed the front-runner. The night of the 2004 caucus is now remembered as much for Dean's news conference, where he appeared to let out a wail. The scream was replayed endlessly on cable television.
REPUBLICAN: George W. Bush ran unopposed.
DEMOCRATIC: Vice President Al Gore won. He secured his party's nomination and lost the presidency. Gore's campaign supported by union workers, was hurt by voters who said they had a negative view of President Bill Clinton, who had been impeached for a sex-and-perjury scandal. Half of those voters favored New Jersey Senator Bill Bradley, according to one survey.
REPUBLICAN: Texas Governor George W. Bush won. He then won his party's nomination and beat Gore for president. In his memoir, Bush's chief political strategist, Karl Rove, boasted about how organized the campaign was by the summer of 1999. "We had fleets of buses that could rival Greyhound and a tracking system that only FedEx or UPS could match," Rove wrote in 2010.
DEMOCRATIC: President Bill Clinton won, running unopposed. Enjoying the hard-fought contest among the Republicans, Democratic National Committee Chairman and Connecticut Senator Christopher Dodd told the press on caucus night: "We feel very good. They have absolutely disemboweled each other."
REPUBLICAN: Kansas Senator Bob Dole won the caucus and then took his party's nomination before losing to Clinton. The longtime senator eked out a victory over conservative commentator Pat Buchanan and former Tennessee Governor Lamar Alexander. Rivals pointed out that Dole had received more support when he won the caucus in 1988.
DEMOCRATIC: Iowa Senator Tom Harkin won the caucus. Clinton, then Arkansas governor, came in third place, winning just 3 percent of the vote. But Clinton would go on to win his party's nomination and the White House. So sure was victory for Harkin that candidates grumbled about skipping Iowa entirely in 1991.
REPUBLICAN: President George H.W. Bush won, running unopposed.
DEMOCRATIC: Representative Dick Gephardt won the caucus. In a state hurt by disappearing manufacturing jobs, Gephardt rode his populist and anti-free-trade rhetoric to victory. Seven weeks after the caucuses, his campaign ran out of money and folded. Massachusetts Governor Michael Dukakis came in third place. Dukakis went on to win his party's nomination and lose the presidency.
REPUBLICAN: Kansas Senator Bob Dole won the caucus. The prairie-raised legislator attracted most of his support from Iowa's rural counties. George H.W. Bush, then vice president, came in third place. Bush countered Dole's early victory by painting his opponent as inconsistent and dubbing Dole, "Senator Straddle." Bush would go on to win his party's nomination and the presidency.
DEMOCRATIC: Walter Mondale, the former vice president, won the caucus. Mondale would go on to win his party's nomination but lose the presidency. Sometimes even winning the caucus is not enough to quiet naysayers. Colorado Senator Gary Hart's strong second-place finish put the senator in the spotlight as the insurgent challenger with bright ideas.
REPUBLICAN: President Ronald Reagan won, running unopposed.
DEMOCRATIC: President Jimmy Carter won the caucuses and his party's nomination, facing an intraparty challenge from Massachusetts Senator Edward Kennedy. Carter had a leg up on the outspoken liberal lawmaker thanks to his previous effort the in 1976 Iowa caucus.
REPUBLICAN: George H.W. Bush, previously CIA director, beat Reagan, then California governor, by 2 percentage points. Reagan would beat Bush in the contest for his party's nomination and win the White House. The Reagan campaign was slow starting. In 1979, the governor, then 69, trailed three opponents in fundraising. Many trace Reagan's performance in a debate against Bush three days before the New Hampshire primary as the turning point in his campaign.
DEMOCRATIC: Eventual party nominee Jimmy Carter, the former Georgia governor, finished 9 percentage points behind "uncommitted," the most popular choice for Democratic caucus-goers that year.
REPUBLICAN: Gerald Ford, who had assumed the presidency when Richard Nixon resigned due to the Watergate scandal, beat out conservative challenger Ronald Reagan. Since 1976, Ford is the only Republican candidate to win a contested Iowa caucus and carry the state in the general election the following November.
DEMOCRATIC: Maine Senator Edward Muskie finished 0.3 percentage point behind "uncommitted," becoming the top vote-getter in the field. South Dakota Senator George McGovern's strong second-place finish propelled the candidate to his party's nomination. McGovern lost the election to Nixon.
REPUBLICAN: The Republicans did not move their Iowa caucus to the front of the primary calendar until 1976. (Reporting By Samuel P. Jacobs; Editing by Alistair Bell and Peter Cooney)
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