Pop music luminary Taylor Swift's decision to wade into electoral politics for the first time on Sunday has driven a spike in US online voter registration, particularly among young people, according to the website Vote.org.
The nonprofit site, which helps people register online, reported 240,000 new registrations since Swift posted a message on Instagram endorsing two Democratic candidates in her home state of Tennessee and urging people to register.
By comparison, the site recorded 57,000 new registrations in all of August and 190,000 last month. About 102,000 of the registrations since Sunday were among voters between 18 and 29 years old, an increase that the site said was likely prompted by Swift's post.
Vote.org acknowledged it was not possible to measure the direct impact of Swift's move.
"But one thing is clear, we're seeing a massive surge in the 18-24 and 25-29 voters," the site said in a statement.
Swift's enormous reach - she has 112 million Instagram followers and 84 million Twitter followers - underscores the way that celebrities can leverage their online presence by sending messages instantaneously to their millions of fans.
The registration deadline is Tuesday in Tennessee and more than a dozen other states.
Swift was scheduled to open the 2018 American Music Awards on Tuesday evening with her first awards show performance in almost three years, the show announced. She will perform "I Did Something Bad" from her multi-platinum album, "reputation".
Polls show the US Senate contest between Democrat Phil Bredesen and Republican Marsha Blackburn, a staunch supporter of President Donald Trump, is virtually tied in a state that Trump won by 16 points in 2016.
Swift, who has largely eschewed politics even as she has become one of pop music's biggest global superstars, told her followers she could not support Blackburn due to the congresswoman's record on women's issues and gay rights.
"In the past I've been reluctant to publicly voice my political opinions, but due to several events in my life and in the world in the past two years, I feel very differently about that now," wrote Swift, who is careful to control her public image.
In addition to Bredesen, Swift endorsed Democratic US Representative Jim Cooper for re-election in a Tennessee congressional race.
Wading into politics can be dicey for artists with roots - and fans - in country music, the dominant genre of red state America. The country crossover band Dixie Chicks generated a firestorm of criticism when the band publicly disavowed the US invasion of Iraq in 2003.
President Donald Trump dismissed Swift as an uninformed voter. "Let's just say I like Taylor's music about 25 percent less now, OK?" he told reporters on Monday.
Former Arkansas Governor Mike Huckabee also chimed in saying her endorsements "won't impact the election unless we allow 13 yr old girls to vote."
Many celebrities identify as liberals, and Democrat Hillary Clinton enjoyed broad support from actors, musicians and other popular figures in 2016.
The most notable celebrity to support Trump may be the rapper Kanye West, who has been invited for lunch with the president at the White House on Thursday.
West and Swift famously engaged in a years-long feud after West interrupted Swift's acceptance speech at the 2009 MTV Video Music Awards to question why she had won.