Democratic presidential candidate Joe Biden paid his female staffers less on average than men over several decades, a new analysis finds.

In his 35 years in the Senate, Biden paid full-time female staffers on average just 67 cents for every dollar earned by their male counterparts, according to an analysis of Senate records by the Washington Free Beacon.

The biggest gap came in 1983 and 1984, when women in Biden's Senate office made less than half of what men made, on average — just 44 cents on the dollar.

A spokesperson for Biden's campaign did not immediately respond to a request for comment from DailyMail.com.

Democratic presidential candidate Joe Biden paid his female staffers less on average than men over several decades, a new analysis finds

This chart of the Washington Free Beacon analysis shows the average pay from men (red) and women (orange) in Biden's Senate office from 1973 to 2008

Biden has often loudly decried the pay gap between men and women, calling equal pay 'common sense' and 'overdue'.

In June, he expressed outrage that the U.S. women's national soccer team is supposedly paid less than the men's team.

'In 2019, it’s past time we close the pay gap and ensure women get paid as much as men,' Biden wrote in a tweet.

It later emerged that the women's team has a different pay structure negotiated through a separate union, and a higher base salary than the men's team.

The men's World Cup bonus is much higher than the women's though, in part because many more people watch the men's tournament.

Biden is seen as a young senator from Delaware. When elected in 1973, he was the youngest sitting Senator at the time

Experts speculate that differences in pay between men and women may be due to discrimination, but it's also possible that factors like experience, voluntary career choices, and family circumstances may play a role.

It's unclear what led to the pay gap in Biden's Senate office that was documented in the analysis.

'Equal pay for equal work. It's common sense. It's also overdue,' Biden wrote in a 2015 tweet while he was vice president.