Democratic presidential candidate Joe Biden has received a wave of backlash for promising to finding a cure to cancer if he is elected in 2020.

"I've worked so hard in my career, that I promise you, if I'm elected president you're gonna see single most important thing that changes America, we're gonna cure cancer," Biden said in Iowa on Tuesday.

When Biden was vice president to President Barack Obama, he had led the "Cancer Moonshot," which resulted in a report outlining recommendations for funding and areas to focus research. Biden also lost one of his sons, Beau, to cancer in 2015.

Many called out Biden's promise as a shameful way to get votes on people's hopes. Other said it not as simple as finding a single cure to the condition.

Dear @JoeBiden cancer is not one disease. The idea that you can “cure cancer” 2 years from now is ridiculous. But you could promise to ban tobacco, that requires zero research dollars and smoking is a co factor in causation of many cancers as well as other diseases. https://t.co/rid2RgqXG4 — Jennifer Gunter (@DrJenGunter) June 12, 2019

The best we could do is invest heavily in science, both basic and applied, and hope to develop more, better, effective treatment options. That would reduce cancer death rates, which have already been falling for 25 years. (Your tax dollars at work!) https://t.co/FD8hPvHkoi — Rob Arthur (@No_Little_Plans) June 11, 2019

I've got various problems with Sanders, but the fact that he's pushing legislation to get health care for people in the territories while Joe Biden is babbling about curing cancer is why I'd vote for him over Biden in a second. — Noah Berlatsky (@nberlat) June 11, 2019

imagine dusting off a 60 year old policy idea from one of the most reviled presidents and being like “I’ve fucking got it, kids" — Listen to @onbeliefpod Li'l 🌳 (@karengeier) June 11, 2019

This is something people said in the 1970s … but a “cure for cancer” is a chimera. Cancer isn’t a single disease. https://t.co/p9sKpBfu48 — keithlaw (@keithlaw) June 11, 2019

Everybody's lost someone to cancer. Promising that you're going to cure it and tying that to your election is an insult, and a foolish one. — Mark Harris (@MarkHarrisNYC) June 11, 2019

Finally, a politician not in the pocket of Big Cancer. https://t.co/goylxPlmhW — Jesse Case (@jessecase) June 11, 2019

Cancer is unchecked cell growth caused by gene mutations - a core component of evolution. Everyone will get cancer if they live long enough. To promise a cure to cancer is extremely misleading. https://t.co/L2QYiCnPMx — John Haydon👨🏼‍💻 (@johnhaydon) June 12, 2019

Some who worked in Obama's administration defended Biden's promise, such as former National Security Council spokesman Tommy Vietor and former speechwriter Jon Favreau.

Hey maybe don't make fun of the guy who just lost his son to cancer for saying he wants to cure it? Maybe just a shred of decency could be applied here? — Tommy Vietor (@TVietor08) June 11, 2019