In 1996, Dole's long list of endorsements from GOP governors "broke his fall" after the front-runner lost the New Hampshire primary to Pat Buchanan, says former Dole campaign spokesman Nelson Warfield.
"It's that little extra ingredient that sometimes makes the difference, and that's why we all crave these endorsements," says New Hampshire state Sen. Lou D'Allessandro, a Democrat who has met with endorsement-seeking candidates for more than 30 years.
Delivering foot soldiers
Few endorsers are as famous or rich as Winfrey. Most are from the political world, sought after for their organizing abilities, political machines or credibility.
"A simple press conference doesn't do a whole lot," says Jim Jordan, a strategist for Democrat Chris Dodd, who got the backing of the International Association of Fire Fighters, but barely registers in national polls. "Endorsements that deliver bodies to work, that deliver infrastructure or fundraising can make a big difference."
Union endorsements, which primarily go to Democrats, provide campaigns with money and foot soldiers. John Edwards, third behind Clinton and Obama in national polls, won the backing of the 1.2 million-member United Steelworkers union. He couldn't get the nod from the national Service Employees International Union, which hasn't endorsed anyone, but Edwards won the backing of 10 of its state boards, representing more than 1 million members.
In early primary states, coveted endorsements also come from local officeholders. "The closer you are to the local level of endorsements, the more they matter," says Larry Rasky, a strategist for Democratic Sen. Joseph Biden, who claims the most endorsements from Iowa state legislators. "They go door-to-door in their districts. They work it hard."
A steady drumbeat of endorsements is designed to make a candidate's nomination seem inevitable: The Clinton campaign announces an endorsement almost every day. But that can backfire, says Contarino, who worked for Walter Mondale's 1984 campaign. "We had every endorsement in the book, and in many ways that ended up feeding a backlash against us as the establishment candidate," he says. "That's dangerous because voters don't like to be told how to vote."
Money and reputations
Endorsements also can lend credibility to a candidate on certain issues. Republican John McCain, a former Vietnam POW who is basing his appeal to voters on his military and national security credentials, is backed by four former secretaries of State including Henry Kissinger, as well as several retired generals in Iowa.
Clinton, trying to convince voters she'll end the Iraq war, won the backing of former senator George McGovern, who ran for president on an anti-war platform in 1972. Romney, seeking to allay worries of Christian conservatives about his Mormon faith, won an endorsement from Bob Jones III, chancellor of fundamentalist Christian Bob Jones University in South Carolina.
Usually, money is as far as a celebrity endorsement goes. "Celebrities are great. Movie mogul Steven Spielberg raised $1.5 million for Obama at a Hollywood fundraiser in February, then raised $1 million for Clinton after he endorsed her in June.
"I would not make the argument that an endorsement (by a celebrity) in and of itself translates into votes," says Andy Spahn, a Hollywood political consultant whose clients include Spielberg. But the money they raise, "if well spent, should translate that into support."
The Oprah effect