Pop musician Taylor Swift made headlines recently when she broke her longstanding silence on political issues and urged her Instagram followers to register to vote.

Her plea — along with her endorsement of two candidates in upcoming Tennessee races for U.S. Senate and House — coincided with more than 166,000 new voter registrations between the time she posted on Oct. 7 and noon on Oct. 9, according to Vote.org. About 42 percent of those registrants were between the ages of 18 and 24.

But are celebrity endorsements really a magic bullet for politicians?

Not necessarily, says Aubrey Jewett, associate professor of Political Science at UCF.

“Studies show that celebrity endorsements most often energize a fan base who were already leaning toward a certain politician. So maybe they go from planning to vote to attending a rally,” Jewett says.

Jewett points to the close primary race between Hillary Clinton and Barack Obama in 2008 as an example. Oprah Winfrey’s endorsement of Obama was estimated to be worth more than a million votes and a huge boost in fundraising.

On a broader scale, celebrity endorsements often serve as a bridge between a demographic and a candidate, explained Terri Fine, professor of Political Science and associate director of the Lou Frey Institute of Politics and Government at UCF. The Institute promotes civic engagement through educational programs, research and policy analysis.

Turnout and registration is often low with younger voters because they don’t frequently see candidates who mirror their age or demographic. Swift’s endorsement serves as a proxy for that lack of a familiar face, Fine says.

“People recognize her, they like her, and that enables her to send a message,” Fine says.

But celebrity endorsements have their drawbacks, too.

“It can actually have a net negative effect,” Jewett explains.

Research shows in some cases voters will come out specifically to vote against someone a celebrity endorsed.

“It can hurt instead of help a candidate,” Jewett says.