"My parents, they have a letter of deportation. I'm scared," the tearful girl told Clinton.
"Come here, baby," Clinton replied, and hugged the girl as she told her to be brave, but not to worry.
"Let me do the worrying. I'll do all the worrying. Is that a deal?" Clinton told her. "I'll do everything I can to help, okay?"
Clinton supports expanded protections for families of young people covered by Obama's "Dream Act" and says she would take other action to keep families together.
The television advertisement running statewide in Nevada urges people to vote in Saturday’s caucuses. Hispanic votes were long presumed to be a given for Clinton, but the senator from Vermont has made inroads there and among white voters. Polls in recent days put the race at a virtual tie, a long fall for Clinton from the double-digit lead she enjoyed before Christmas.
Clinton met with young people on her first campaign trip to Nevada last spring, and pledged then to go further than Obama to protect other classes of illegal immigrants. She supports a path to citizenship for those residing in the United States illegally, which would require congressional action.
Both Clinton and Sanders were campaigning in Nevada on Thursday.
In previewing the new ad Wednesday night, a statement from Clinton's campaign noted her support for a bipartisan Senate immigration reform bill in 2013. That effort failed. "Unlike Senator Sanders, she supported the 2007 bill as well," the statement said, referring to a previous failed effort that came before the Senate when both she and Sanders served there.