Celebrity endorsements have become par for the course in US elections. It's not unusual for your favorite athlete to voice support for a presidential candidate, or for actors to show up at party nominating conventions. Sure, politicians are always happy to have someone famous drumming up votes for them, but endorsements are not generally a huge deal.

Unless, that is, they come from singer-songwriter Taylor Swift.

Swift, who is arguably the biggest pop star on the planet right now, shared a statement of support for Democratic presidential candidate Kamala Harris on Instagram the night of last week's TV debate between Harris and her Republican rival for the White House, Donald Trump.

The news garnered almost as much coverage as the debate itself. Tim Walz, Harris's running mate, was told about the endorsement live on air and couldn't stop smiling.

Why do some words of support from a singer make a vice presidential candidate look like Christmas came early? Why do they matter enough for Trump to post "I hate Taylor Swift!" in all caps on his social media platform Truth Social?

Could Swift's push make 'the difference between winning and losing?'

"In a close election, [Swift's endorsement] could matter a great deal," Richard Longoria, an associate professor of political science at the University of Texas Rio Grande Valley, told DW in an email.

Looking at the numbers underlines this. In addition to her endorsement, Swift posted an Instagram story encouraging her followers to register to vote. The custom link to the nonpartisan website vote.gov that she shared along with that call to action received more than 405,000 visitors in one day (Instagram stories disappear 24 hours after they're posted).

That doesn't mean Swift got 405,000 people to register to vote. Vote.gov merely directs people to their state's election website, where the actual registration would take place. But even if only half of the people who clicked on Swift's link registered to vote, it could make a difference.

"If she persuaded her fans to register to vote and to support Kamala Harris, those numbers could be significant," said Longoria. "To win a presidential election in the US, a candidate needs to win a sufficient number of states. A few thousand votes in just a few states could be the difference between winning and losing."

Swift's endorsement noticed by people who don't follow politics

Staunch Trump supporters aren't going to be swayed by Swift's statement. But it could spur people into action who would normally stay home on Election Day.

This is particularly significant, since many of Swift's fans are younger Americans, millennials (born roughly between 1981 and 1996) and Gen Z (born roughly between 1997 and 2012). Millions of Gen Z voters will be eligible to head to the polls for the first time in their lives in this election. And younger Americans are, on average, less likely to vote.

In 2022, adults under the age of 50 made up only 36% of all voters, according to the Pew Research Center. If Swift's call to action can bring some of these previous non-voters to the polls, Harris is likely to benefit. 

Celebrity endorsements like Swift's "are also noticed by people who are not interested in politics and take little or no note of election- and political media coverage," communication scientists Cordula Nitsch and Katja Friedrich, who have done a lot of research in the field of politics and entertainment, said in a statement shared with DW. "Taylor Swift has 284 million followers on Instagram! And endorsements like this often serve as a hook for further reporting in the media and thus reach an even larger audience."

The singer's outreach power became clear last year. On National Voter Registration Day 2023, Swift had also shared a brief message via Instagram encouraging her fans to register to vote. Vote.org reported that 35,252 new registrations were recorded that day, a number 23% higher than on the same day in 2022. While it's unclear how many of the registrations were tied to Swift's message, Vote.org reported a 1,226% jump in participation in the hour after the post.

Celebrity endorsements can 'tip the scales'

Usually, Longoria said, "partisanship is the strongest predictor of vote choice; Democrats vote for Democrats and Republicans vote for Republicans."

So while there have been cases where celebrities speaking out ahead of elections had an impact — aside from Swift, TV host Oprah Winfrey's endorsement of Barack Obama in the 2008 election was also considered important, for example — they don't usually sway determined voters.

"Endorsements attract a lot of attention, but they won't influence voters who have a solid political opinion," said Nitsch and Friedrich. "But when there's a large number of undecided voters and the candidates are neck-and-neck, an endorsement can be the thing that tips the scales."

Polls in the US show that the race between Harris and Trump is a very close one. While it will be impossible to determine exactly what impact Swift's endorsement of Harris had, the race's outcome is expected shortly after Election Day on November 5.

Edited by: Martin Kuebler