Joe Biden with wife Jill (L) and sister Valerie (R) (Getty Images/Frederic J. Brown/AFP)

Democrat presidential hopeful Joe Biden confused his wife and sister last night during a speech celebrating his primary wins on Super Tuesday.

“By the way, this is my little sister, Valerie,” the former vice president said, turning to his right and reaching out and grabbing his wife's hand.

“And, I’m Jill’s husband,” Biden added, pointing to his sister on his left.

Biden, then, caught himself and made the correction – blaming the two women for the mistake:

“Oh, no! This is…hell, you switched on me! This is my wife. This is my sister. They switched on me.”

But, in fact, his wife and sister did not switch on him: Jill had been on his right and Valerie on his left the from the moment they took their places on the stage.

Later, in the same speech, Biden promised that he would find a cure for Alzheimer's disease.

“We’re going to invest billions of dollars to find, and I promise you, cures for cancer, Alzheimer’s and diabetes," he said.