Credit: Alo Ceballos/GC Images

Madonna expressed herself as only she can with a surprise acoustic concert in support of Hillary Clinton on Monday night in New York City, just hours before the polls were set to open.

Rallying her fans and fellow Clinton supporters to Washington Square Park via social media, the Material Girl performed such songs as “Don’t Tell Me,” “Like a Prayer,” “Express Yourself,” and John Lennon’s “Imagine,” while the crowd sang along.

According to the Associated Press, Madonna performed for 30 minutes and said the concert was “about unifying us and keeping America great, not making America great again.” Wearing a stars-and-stripes knit cap, she added, “We’re going to elect a president that does not discriminate.”

The pop star has been a staunch supporter of Clinton throughout her campaign, and recently made headlines with a racy offer for those voting for the Democratic nominee. See some highlights from Madonna’s concert below.