Storm Lake, Iowa (CNN) Democratic presidential candidate Sen. Elizabeth Warren on Saturday said former Vice President Joe Biden needs to provide an answer to allegations he inappropriately touched a Nevada politician at an event in 2014.

Lucy Flores, the former Democratic nominee for lieutenant governor of Nevada, made the allegations against Biden in an essay for The Cut, an arm of New York magazine, writing that Biden made her feel "uneasy, gross, and confused" in 2014 when, at a campaign rally in Nevada, she said he kissed her on the back of the head. Biden does not recall any impropriety, a spokesman said.

"I felt him get closer to me from behind. He leaned further in and inhaled my hair. I was mortified," Flores wrote, adding that she wondered why the then-vice president had come that close to her. "He proceeded to plant a big slow kiss on the back of my head. My brain couldn't process what was happening. I was embarrassed. I was shocked. I was confused."

"I read the op-ed last night," Warren said in Iowa on Saturday. "I believe Lucy Flores. And Joe Biden needs to give an answer."

At the same event in Iowa, former secretary of Housing and Urban Development and Democratic presidential candidate Julián Castro told reporters he too believed Flores and added, "we need to live in a nation where people can hear her truth."

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