Fourteen US women senators pressed Saudi Arabia's King Abdullah in a letter Tuesday to lift his country's unique ban on women drivers, calling it a big step forward on human rights.
"We strongly believe it is time to abolish the prohibition on women driving once and for all, especially in light of Saudi Arabia's role as a newly elected member of the board of UN Women -- an entity dedicated to achieving gender equality and the empowerment of women worldwide," they wrote.
The group was led by Democratic Senators Barbara Boxer and Mary Landrieu.
Signing the letter were Democratic Senators Dianne Feinstein, who chairs the Senate Intelligence Committee, Patty Murray, Claire McCaskill, Barbara Mikulksi, Jeanne Shaheen, Maria Cantwell, Kirsten Gillibrand, Debbie Stabenow, Amy Klobuchar, Kay Hagan, and Republican Senators Olympia Snowe and Susan Collins.
They noted the king's appointment of the first woman deputy minister in Saudi Arabia and the establishment of a university that allows women to study alongside men and permits women to drive motor vehicles on campus.
"These are important steps, but more must be done and lifting the driving ban would be a critical step forward," they wrote.
Saudi Arabia is the only country in the world that prevents women from driving.
There is no law banning women from driving, but the interior ministry imposes regulations based on a fatwa, or religious edict, stipulating that women should not be permitted to drive.
A group of defiant Saudi women got behind the wheels of their cars on June 17 in response to calls for nationwide action to break the ban.
US Secretary of State Hillary Clinton publicly threw her support behind the campaign, saying that "what these women are doing is brave, and what they are seeking is right."
The icon of the campaign was Manal al-Sharif, a 32-year-old computer security consultant, who was arrested on May 22 and detained for 10 days after posting on YouTube a video of herself driving her car around the eastern city of Khobar.
Women in the kingdom must hire drivers, or depend on the good will of male relatives if they do not have the means.