The difference between average annual salary for men and women in the federal work force declined from 19 cents to 11 cents on the dollar between 1998 and 2007, according to a draft report from the Government Accountability Office.
The draft, obtained by The Associated Press, is set for release Tuesday at a hearing of the Congress' Joint Economic Committee.
All but 7 cents of the gap can be accounted for by differences in measurable factors, such as differences in education levels and the type of jobs men and women had, the report said. The gap narrowed the more men and women shared characteristics, including the jobs held, levels of experience and education.
The GAO said factors such as work experience outside government and discrimination may account for some or all of the remaining gap.
New York Rep. Carolyn Maloney, who chairs the Joint Economic Committee, said the report shows the need for federal legislation to address the remaining pay gap.
"As families continue to struggle during this economic crisis, they should not also be robbed by discrimination against women in the labor market," Maloney said.
The gap among federal employees has been steadily shrinking since 1988, when female government workers earned 28 cents on the dollar less than their male co-workers.
In the general work force, a previous GAO study found that women earned on average 20 cents less for every dollar earned by men in 2000 when differences for occupation, work patterns, marital status and other factors were considered.
Maloney and other congressional Democrats have been trying for years to pass pay equity legislation that would treat gender discrimination involving pay in the same as race, disability and age discrimination.
The bill, known as the Paycheck Fairness Act, would allow for compensatory and punitive damages, ban employers from retaliating against workers who share salary information with colleagues and require employers to prove that paying a woman less than a man is job-related and necessary.
The measure, which passed the House last year but stalled in the Senate, could have new life under President Barack Obama and the increased Democratic majority in Congress.