Singer Katy Perry took centre stage as a guest during Hillary Clinton's latest campaign in Iowa. She treated the crowd with her two inspiring singles "Firework" and "Roar".

The singer wore a white strapless dress complete with a Star-Spangled Banner cape and was presented by former US pressident Bill Clinton, reports aceshowbiz.com.

"I've never been the warm-up act for Katy Perry before, but I am well aware that I am the warm-up act," Bill said.

Explaining why she supported the Democratic presidential candidate, Perry said: "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."

She also took over Hillary Clinton's Instagram and shared a selfie with the politician, showcasing her Hillary-inspired nails and a POTUS necklace she purchased as a birthday gift for her.