Singer Katy Perry and reality TV star-turned-fashion designer Nicole Richie have thrown their support behind self-help author Marianne Williamson's campaign to run for a seat in the US Congress.

Williamson has bid to replace Democratic representative Henry Waxman, who is retiring from California's 33rd Congressional District, reports contactmusic.com

The stars joined guests, including reality TV stars Kourtney and Kim Kardashian for the political campaign event in Los Angeles Tuesday.

Richie has also recorded a video testimonial for the writer and aspiring politician, which showed: "I support Marianne Williams because I think that America is ready for positivity, strength and enlightenment."

Celebrities like Eva Longoria, Glee star Jane Lynch, and singer Alanis Morissette have also voiced their support for Williamson's race for a seat in America's House of Representatives.