A senior adviser to Michael Bloomberg's presidential campaign criticized Sen. Bernie Sanders (I-Vt.) on Tuesday over a 1972 essay he wrote that mentioned women fantasizing about rape, describing it as "loopy stuff."

"We have a candidate who has risen in the polls because of this track record," Bloomberg senior adviser Tim O'Brien told CNN's "New Day" co-anchor Alisyn Camerota. "[But] Bernie has loopy stuff in his background, saying women get cancer from having too many orgasms or toddlers should run around naked and touch each other's genitals to insulate themselves from porn."

"Sir, what?" an incredulous Camerota replied.

"He's written about women's rape fantasies. That hasn't been surfaced. That's the loony side of Bernie," O'Brien added.

The Hill has reached out to the Sanders campaign for comment.

The attack comes ahead of Tuesday night's Democratic debate in South Carolina, where Sanders is expected to be the main target after his decisive win in Nevada's caucuses on Saturday.

The victory in Nevada underscored that Sanders is the clear front-runner for the Democratic Party's presidential nomination, and it was doubly bad for Bloomberg coming after his disastrous initial debate performance days earlier.

He and a number of Sanders rivals are now trying to figure out how to blunt the progressive candidate's momentum, and the mentioning of the 1972 essay is likely a sign of the attacks to come.

The essay was first reported by Mother Jones in 2015, the last time Sanders was running for president.

Sanders began the essay written for the Vermont Freeman, an alternative newspaper, by writing about men's and women's sexual fantasies. His point was that gender roles can create troubling dynamics in people's sex lives.

The Sanders campaign distanced itself from the essay in May 2015, with then-Sanders campaign spokesman Michael Briggs saying the article was a "dumb attempt at dark satire in an alternative publication" that "in no way reflects his views or record on women."

- This report was updated at 10:43 a.m.