WASHINGTON — Former Vice President Joe Biden says that he'll cure cancer if he's elected president.

Speaking at a campaign stop in Ottumwa, Iowa, on Tuesday he discussed losing loved ones before making his promise.

"A lot of you understand what loss is and when loss occurs, you know that people come up to you and tell you 'I understand' if you lose a husband, a wife, a son, a daughter, a family member," he said. "That's why I've worked so hard in my career to make sure that — I promise you if I'm elected president, you're going to see the single most important thing that changes America, we're gonna cure cancer."

The statement drew applause from the audience.

Biden has taken the lead on cancer issues before. He lost his eldest son, Beau Biden, to brain cancer, in 2015. The former vice president was tasked with leading President Barack Obama's "Cancer Moonshot" initiative to find a cure for cancer in the last year of the Obama administration.

Former Vice President Joe Biden campaigns in a packed hall in Ottumwa, Iowa Tuesday, June 11, 2019. (Via OlyDrop)

After leaving office, Biden helped lead the Biden Cancer initiative at the University of Pennsylvania, which aims to "develop and drive implementation of solutions to accelerate progress in cancer prevention, detection, diagnosis, research, and care, and to reduce disparities in cancer outcomes." He left that role when he announced his bid for president.

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After his comments, Biden was heckled by a protestor. The audience booed the man, but Biden responded calmly.

"No, no, that’s OK. No, no, no," Biden said. "This is not a Trump rally. Let him go."

The former vice president had been going through Iowa on several campaign stops at the same time as President Donald Trump. Biden called Trump an "existential threat" to the United States. Trump, for his part, criticized Biden for his age and for being "weak mentally."

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This article originally appeared on USA TODAY: Joe Biden says 'we're gonna cure cancer' if he's elected president