Federal contractors and subcontractors accounting for nearly a quarter of the nation's workforce, so the proposal could have a major impact in bringing down the 13 percent unemployment rate for disabled workers. That's about 1 1/2 times the rate of those without disabilities.

There are about 200,000 federal contractors taking in approximately $700 billion in contracts.

The government long has used the leverage of federal spending to promote affirmative action in the hiring of women and minorities. The new rule would, for the first time, give that same treatment to people with disabilities.

The proposed rule is not a quota. It would require companies to devote more resources on recruiting efforts to hire more disabled workers, improve training programs and update data collection.

Contractors would have to keep detailed records showing they are complying. The rule would require them to list job openings to increase their pool of qualified applicants.

"For nearly 40 years, the rules have said that contractors simply need to make a 'good faith' effort to recruit and hire people with disabilities," Shiu said. "Clearly, that's not working."

Disability advocates have pressed for a rule that could help stem the pervasive unemployment and underemployment for the disabled. But businesses have had mixed reactions to the plan, which could prove easier for larger companies to put in place than smaller ones that face increased costs and paperwork.

The government has struggled over the years to increase job opportunities for disabled workers. Among working age people with disabilities, 79 percent are outside the labor force altogether, compared with 30.5 percent for those without disabilities, according to the Bureau of Labor Statistics.

The rule would apply to those contractors with at least 50 employees that have a minimum $50,000 in government contracts. That currently includes about 170,000 contractors.

By contrast, the ADA applies to employers with 15 or more workers. That law prohibits discrimination against the disabled, but does not require businesses to set a specific goal for hiring disabled workers.

Labor officials would monitor compliance with the new rules through annual audits, which are currently performed on about 4,000 contractors each year.

Companies failing to comply could be ordered to make back-payments to those denied employment or change training policies and procedures. In rare cases, the agency could seek a court order to bar a company from bidding for federal contracts.

"I think providing these sorts of measurable clear steps will give contractors the guidance and the clarity they need," Shiu said.