The daughter of the principal killed in the 2012 Sandy Hook Elementary School shooting is featured in an emotional new ad for Democratic presidential front-runner Hillary ClintonHillary Diane Rodham ClintonButtigieg stands in as Pence for Harris's debate practice Senate GOP sees early Supreme Court vote as political booster shot Poll: 51 percent of voters want to abolish the electoral college MORE.

In the ad, titled "My Mom," Erica Smegielski, the daughter of Dawn Hochsprung, tells the story of how she lost her mother.

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Smegielski says in the beginning of the ad that her wedding was one of the last things she planned with her mom.

"It was a very bittersweet day, because it's just all one big reminder of the giant hole where she used to be," she says.

"My mom was my best friend," she adds, as pictures flash of Smegielski and her mother.

Her mom was murdered while "trying to protect the children in her care from a gunman," she continues in the ad.

"No more families should have to go through what we have. Hillary Clinton is the only candidate that has what it takes to take on the gun lobby."

Smegielski concludes that Clinton is fighting harder than anyone to reform the country's gun laws, adding that the Democratic front-runner reminds her of her own mother, as a clip of her hugging Clinton is shown.

"She isn't scared of anything, and that's how I know that she is the person that can actually make a difference," she says. "That's why I believe in her. That's why millions of other Americans believe in her. There's finally someone who can change things."

A 60-second version of the ad began airing in Hartford, Conn., on Wednesday. A 30-second version will air in Rhode Island, Hartford and Fairfield County — where Sandy Hook is located.

Smegielski joined Clinton on Tuesday night at a campaign event, where the candidate spoke about Smegielski's story.

“She'd never been involved in politics before, but she has made it her mission to advocate for common-sense gun safety reform. Like the mothers of Eric Garner and Trayvon Martin and so many others, Erica has turned her sorrow into a strategy and her mourning into a movement,” Clinton said.

Smegielski will also join Clinton and other people and families impacted by gun violence Thursday for an event in Hartford.
 
Clinton has a small lead in Connecticut's primary, which is on April 26. 
 
 
Earlier this month, she blamed Sanders's home state of Vermont for selling many of the guns used to commit crimes in New York. She also went through a list of the Vermont senator's past votes on guns, including opposition to background check bills.
 
Clinton won a commanding victory in the New York primary.