U.S. Senator Barbara Boxer (D-CA) and other members of Congress this week sent a letter to President Barack Obama in advance of the United Nation’s upcoming election for Secretary-General, urging the United States to “reaffirm the UN’s founding principle of equality by encouraging the strong consideration of candidates for the first female Secretary-General.”

At the end of this year, the term for the current United Nations (UN) Secretary-General Ban Ki-moon will end. In the more than 70-year history of the UN, there has never been a female Secretary-General.

“Numerous studies have shown that women’s meaningful representation in decision-making around peace and security issues is key to the effectiveness and sustainability of these efforts,” the senators wrote in the letter. “Additionally, a female Secretary-General would bring a different perspective on the numerous challenges facing the UN and would help to ensure further dedicated attention to gender throughout the organization.”

The letter noted the lack of representation of women in top leadership positions at the UN, with men appointed to nearly 92 percent of high-level senior positions. Despite Secretary-General Ban’s previous efforts to promote women to senior leadership positions, men have since replaced many of these female leaders.

In 1997, the UN General Assembly adopted a resolution that called for the consideration of regional rotation as a part of the election of Secretary-General as well as gender equality. While the UN has upheld the consideration of regional rotation, it has not given full consideration to gender equality.

Under the terms of the UN Charter, all member states are allowed to nominate potential candidates to the Security Council. The recommendation of the Security Council requires at least nine votes in favor, out of the 15 members, and must include the support of all of the five permanent members.