Opposition lawmakers walked out in protest as the Lower House on Friday passed a contentious bill to revise the worker dispatch law, ending a requirement that companies upgrade their temporary workers to fully fledged employees after a period of three years.

The bill to revise the worker dispatch law was approved by a majority in the Lower House, after it secured approval earlier in the day from the House of Representatives Committee on Health, Labor and Welfare. It now goes to the Upper House for deliberation, but is nevertheless expected to be enacted as law by the end of the current Diet session.

Opposition parties protest that the bill will only benefit businesses and do nothing for the job security of dispatched workers, who lack many of the guarantees and benefits enjoyed by regular staff.

Health ministry data shows that 1.26 million people were working as temps as of 2013.

The revision is likely to be enacted as law by the end of the current Diet session, which is scheduled to end on June 24 but expected to be extended into the summer.

The law in its current form puts a three-year limit on the use of temporary workers supplied by staffing agencies. The only exceptions are those engaged in 26 jobs designated as requiring specialized skills, including interpreters and secretarial positions.

The revision would scrap this three-year limit, allowing businesses to use cheap, no-ties temps for as long as they want, on condition that employers “take labor union opinions” into account. Companies would then have to either swap out the workers for new temps or hire them as full-time employees. It would also abolish the exemption for 26 specialized job categories and place a blanket three-year cap on all temporary workers on doing the same jobs continuously. This means, for example, those who have worked as interpreters would need to find a new job every three years unless their end-users decide to take them on their permanent payroll.

Of all temporary staffers in 2013, some 490,000, or about 40 percent, were within the 26 designated categories.

The bill’s backers say the new rules would help temps land a regular job. If they work for three years in the same job, dispatch agencies will be required to ask the company to hire them directly. If the company declines, the agency must either find the individual a new temporary job or switch the dispatch contract to a new, indefinite-term contract. Over 80 percent of temporary staff currently have fixed-term contracts with their dispatch agencies.

But critics say such steps are of little use in encouraging businesses to directly hire workers, as they only go as far as asking the agencies to “ask” the company to take on the worker, on a nonbinding basis.

During the Diet session on Friday morning, Prime Minister Shinzo Abe insisted that the revision would benefit dispatch workers.

Members of the opposition Democratic Party of Japan and Japanese Communist Party blasted the bill and demanded its abolition. They argue the revision would increase, rather than mitigate, job insecurity because temps could become locked in a cycle of losing their job every three years.

But their voices rang hollow in the powerful lower chamber, where the ruling camp holds two-thirds of the seats.

This is the Abe administration’s third attempt to revise the worker dispatch law. Two previous bills were scrapped, once because of the sudden dissolution of the Lower House last year, and once because minor drafting errors were identified in the text.

Meanwhile on Friday, the Lower House also passed a bill that aims to rectify pay disparities between temporary workers and full-time, direct-hire employees who perform the same jobs.

But the bill, originally submitted by a joint opposition force including DPJ and Ishin no To (Japan Innovation Party), was effectively watered down after Ishin reached a deal with the ruling camp and revised its contents.

Ishin, the LDP, and Komeito changed the wording in the section of the bill that calls for what the sponsors call the principle of “equal job, equal pay” and made it more ambiguous.