Massachusetts Sen. Elizabeth Warren, who is running for president in 2020, responded to a recent accusation that former Vice President Joe Biden, who is rumored to be considering a run, inappropriately kissed and touched a Nevada assemblywoman during a 2014 campaign event.

Warren said she was not familiar with the specific accusation, but " if there's a problem, then Joe Biden needs to answer."

A spokesman for Biden said he was never aware of the woman being uncomfortable, but respected her decision to express her feelings.

Democratic Sen. Elizabeth Warren of Massachusetts, who is running for president in 2020, addressed the recent article by a former Nevada assemblywoman claiming that former Vice President Joe Biden inappropriately kissed and touched her during a 2014 campaign event.

Warren became the first 2020 candidate to address the accusations, saying Biden needed to answer for them, but admitted she was not entirely familiar with the specific claim.

Read more: Joe Biden's 'awkward' interactions with women resurface following allegations of inappropriate touching

"So I don't know anything about this," Warren said. "But obviously if there's a problem, then Joe Biden needs to answer."

Warren made the comments Friday night to a group of reporters at a campaign event in West Des Moines, Iowa, according to local news reports. The campaign event was her third of the day.

The following day at a campaign event in Iowa, Warren addressed the accusations further.

"I read the op-ed last night," she said. "I believe Lucy Flores and Joe Biden needs to give an answer."

Responding to a question as to whether Biden should rethink running for president, Warren said, "That's for Joe Biden to decide."

Biden's behavior has been thrust back into the spotlight as he considers running for president in 2020, which would be the third attempt of his political career.

Read more: Elizabeth Warren is running for president in 2020. Here's everything we know about the candidate and how she stacks up against the competition.

Still, many national polls place Biden at the very top for Democratic voters. According to a recent INSIDER poll, Biden benefits from near-universal name recognition, with 82% of respondents having heard of him.

In addition, Democratic voters are most confident in Biden's ability to unseat President Donald Trump in the general election, with 71% believing he would win in a head to head matchup. Just 5% said they think Biden would lose to Trump.