Katy Perry Performs at Hillary Clinton Rally in Iowa

Katy Perry performed at a rally for Hillary Clinton in Des Moines, Iowa on Saturday.

The 31-year-old singer donned a white strapless Michael Costello dress and an American flag cape adorned with crystals, according to Us Weekly. She performed a few of her big hits, such as "Roar," "Wide Awake" and "Firework," along with "America the Beautiful." The pop singer also told the crowd to vote for Clinton.

"You have so much power and this is one of the most important elections in over a decade," Perry said to the audience. "So much change can happen. I stand and I march with Hillary. I believe in her future, her vision. I believe in her policies. I believe in equal rights for men, women, pay ... Thank you for having me, she's my firework."

Bill Clinton was also on hand at the event and introduced Perry to the stage.

"Look, I don't want to talk long, because I have never been the warm-up act for Katy Perry before. I am well aware I am the warm-up act," the 69-year-old former U.S. president said.

In addition to her performance at the rally, Perry also took over Clinton's Instagram account for the day. She posted a photo of her manicured nails, which showed off Clinton's campaign logo.

"Katy Perry here, taking over Hills' IG today for the rally in Iowa. The stage is set, and the nails are pressed. T-minus 1.5 hours before we Roar together. #ImWithHer - Katy," she captioned the photo. In another post on Instagram, Perry and Clinton took a selfie together, which was captioned "#ImWithHer - Katy."

Clinton has used Perry's song "Roar" several times during her rallies, since she agrees with the song's message.

"You know, sometimes it's important, you just have to roar about what you need to fight for," Clinton said following Perry's performance.

Perry also gave Hillary a birthday gift: a gold necklace that said "POTUS."