"Prepping her performance for President Obama’s rally, Katy Perry belted out her tunes in Las Vegas, NV on Wednesday (October 24).
The “California Girl” songstress opted for a casual ensemble in a white tank top and grey sweatpants, while on stage for afternoon rehearsal."
(SOURCE: http://celebrity-gossip.net/katy-perry/katy-perry-ready-perform-president-obama-vegas-749653)