WATCH: Lady Gaga performs "Till It Happens To You" in a rally against sexual assault in Las Vegas.

Lady Gaga joins United States Vice President Joe Biden in a rally against sexual assault at the University of Nevada Las Vegas on Thursday. Gaga delivered an emotional performance of her song "Till It Happens To You" at the event which is called "It's On Us", a rally launched by the Vice President that aims to bring awareness and collective responsibility to the epidemic of sexual assaults on college campuses. As part of it, Biden is set to visit several colleges and universities across United States.


Asked why Lady Gaga is a good ambassador for this particular cause, the Vice President told Billboard: "Lady Gaga is brave and sincere. She’s a survivor who has the courage to speak out, and I know how difficult that can be. We’ve talked at length and I admire her courage. She encourages so many other women to step forward."


Check out some HQ photos and watch Gaga's performance below.