A new report claims that former Vice President Joe Biden spent 35 years paying his female staff members less than his male staffers.

Biden never achieved pay equity in those years and paid women less than 50 percent of what men were paid at certain points, The Washington Free Beacon reported Wednesday.

The conservative outlet found those figures by analyzing data from the biannual report of the secretary of the Senate, which covers six-month periods. Staff not employed for the entirety of those periods weren't included in the analysis.

The Beacon's report came as Biden fought to maintain his front-runner status in the 2020 race, where issues surfaced surrounding his long tenure of public service.

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Biden has long advocated for equal pay and in June called out the pay gap between the U.S. women's and men's soccer teams.

“In 2019, it’s past time we close the pay gap and ensure women get paid as much as men," he said at the time.

Critics have argued that statistics on women's pay fail to take into account differences in the types of jobs they perform. For example, The Daily Wire's Ashe Schowe previously wrote that female soccer players didn't make as much money because they attracted less interest, and therefore less ad revenue.

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It's unclear why Biden paid his female employees less. His campaign did not immediately respond to Fox News' request for comment.

According to the Free Beacon, Biden came close to achieving pay equality in 2002 but the gap widened in 2008.

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The Beacon's Collin Anderson reported: "Women garnered as little as 44 percent of what Biden's male employees made in 1983 and 1984 ... During Biden's final months as a senator in 2008, the gender pay gap again widened, as women in his office earned 66 percent as much as men -- a gap 11 percentage points wider than the 2008 national average, according to the National Committee on Pay Equity."

According to another analysis, the White House paid women less when Biden served under former President Obama's administration.