The stardust is tarnished, and the glow dimmed. Celebrity endorsements have come to mean little in politics, according to a study released Monday by researchers at North Carolina State University.
Voters — particularly young voters — are not swayed by the opinions of the famous when they get into the voting booth. Sometimes they even dislike candidates who dally with the likes of, say, George Clooney.
"The positive effects of a celebrity endorsement are minimal for politicians," said Michael Cobb, an associate professor of political science who led the research.
"I began to observe this kind of sentiment among my own students — particularly my conservative students — who were continually commenting about how much they disliked celebrities wading into politics," he said. "And I knew there was some research to be done."
Using theoretical voting scenarios and invented headlines about partisan Hollywood, the research team plumbed the feelings of more than 800 college students, evaluating whether endorsements from celebrities — including Mr. Clooney and Madonna — would affect their voting behavior.
"We found that celebrity endorsements do not help political candidates. They can hurt them," Mr. Cobb said. "In one of the studies, for example, we found that by exposing young people to a celebrity endorsement, they liked the candidate less and were less likely to vote for him."
The findings also apply to voters in other age groups, he said.
Public annoyance with celebrities who leave the soundstage for the campaign trail has been detected elsewhere. A Pew Research Center survey released as the 2008 presidential campaign was well under way found that three-fourths of the respondents said the endorsements of Jay Leno, Bill Gates, Kanye West, Angelina Jolie, Jon Stewart, Donald Trump and others would make "no difference" in influencing their votes.
That did not deter the famous.
Candidate Barack Obama racked up so many celebrity endorsements that Time magazine categorized the phenomenon as "Obama's celebrity army." Robert De Niro, Chris Rock and Ron Howard were among the many celebrated soldiers, along with Oprah Winfrey, of course.
Miss Winfrey succeeded in her much-publicized quest to elect Mr. Obama, at least according to research conducted at the University of Maryland in the aftermath of the election. Analysis of voter turnout and socioeconomic factors determined that the TV talk-show maven held plenty of sway.
"In total, we estimate that the endorsement was responsible for 1,015,559 votes for Obama," the analysis said.
"And that was all interesting, because in the wake of her support for candidate Obama, Oprah's ratings went down. The raw data at the time suggested her popularity declined," Mr. Cobb said. "So there can be a negative effect on the image of a famous person, too."
That has much to do with public perceptions of our stars.
"Twenty or 30 years ago, a celebrity was a celebrity. The image didn't change much. John Wayne was 'John Wayne' for decades. These days, with nonstop media coverage, a celebrity's image changes from month to month," said Mr. Cobb, who also asked his respondents to rate the credibility and trustworthiness of the stars.
Such inconsistencies can get in the way of a carefully calibrated political campaign, the studies found.
"Even when voters perceive that the celebrity is trustworthy, the equation changes when they weigh in on politics," Mr. Cobb said.
But he doesn't discount the fame factor altogether. While the impact of a celebrity endorsement is "minimal," there are circumstances — political rallies, for example — when such an endorsement may be helpful to a candidate.
"Are you more likely to attend a political event if the candidate is slated to appear by him- or herself, or if the candidate is going to appear with Madonna?" Mr. Cobb asked.
"Endorsements may also help candidates distinguish themselves from a crowded field during primaries," he added.