Hillary Clinton's campaign tested whether a Washington Free Beacon report showing that Clinton paid women much less than she paid men working in her Senate office would damage her standing with Iowa voters, according to emails released by WikiLeaks.

On the same day the Free Beacon reported that women in Clinton's office were paid just 72 cents for each dollar paid to men, campaign pollsters discussed showing the article to "vulnerability groups" it was organizing in Iowa.

John Anzalone, one of the Clinton campaign's main pollsters, sent the link to his partner David Binder a few hours after it was published on February 23, 2015.

About a week later, Anzalone circulated the draft text of a "vulnerability poll" that included two questions on the gender pay gap issue, according to the emails.

"[Hillary Clinton] says she supports equal pay for women, but in her own Senate office only paid women seventy two cents on the dollar compared to men," the poll stated, asking voters to respond whether this made them more or less likely to vote for Clinton.

A separate question, titled "Bad for Women," gave more detail. It was included in a section that gave voters "a list of things critics might say about Hillary Clinton," and asked them to rate both the believability and effectiveness of the attack.

"Hillary Clinton portrays herself as a champion of working women, but Clinton only paid women in her own Senate office seventy two cents on the dollar compared to men," the poll said. "Women in Clinton's office made fifteen thousand dollars a year less than men. And at the Bill and Hillary Clinton Foundation, men on the senior staff get paid an average of over a hundred thousand dollars a year more than women on the senior staff."

The portion about the Clinton Foundation was based on the campaign's internal research, according to emails previously reported by the Free Beacon.

The campaign was notified by its own researchers that "there are huge discrepancies" at the foundation and warned that it would likely be attacked. Included in the email was research showing that the pay gap between the average male salary and average female salary exceeded $100,000.

The results of the vulnerability poll are unknown. Neither Anzalone or the campaign immediately responded to requests for comment.

The Free Beacon has since discovered major gender pay gaps at Clinton's State Department and presidential campaign.

The Clinton campaign has previously confirmed the accuracy of the Free Beacon's data.