Lovato opened for the former secretary of State by performing some songs during a campaign stop at the University of Iowa.
“Oh my gosh, I am so happy to be here, but I have to tell you I am so thrilled that Demi is here with us,” Clinton said.
Clinton, who spoke briefly following Lovato’s performance, used the moment to praise the singer for her activism and her role in the campaign.
“You already know what an extraordinary talent she is, and you got a taste of that tonight,” she said.
“I want to thank her for how brave she is, how confident she is. Because she is using her voice not only to sing and inspire us through that, she’s using her voice to reach out to so many people who need a little bit of help themselves.”
Clinton also took the opportunity to motivate the young crowd to support her in the upcoming Iowa caucuses.
“I’m proud of the progress we’ve made under President Obama, and I don’t want anybody sending us back,” she said.
“And how are we going to take on those big special interests who are always trying to put the wall against the kind of progress we believe in? I’m going to take them on, whether their insurance companies, or banks, drug companies or the gun lobby. We’re not going to let them have their way.”
Clinton has a slim lead over rival Bernie Sanders in Iowa polls, less than two weeks before the caucuses.