A federal district judge has dismissed legal challenges to a National Labor Relations Board final rule shortening the length of time between union elections.

The so-called “microwave rule,” which was challenged by the U.S. Chamber of Commerce and Coalition for a Democratic Workplace, went into effect Monday. The final rule was published in the Federal Register in December.

Long-term care providers have argued that the rule drastically quickens unions’ elections process. Providers have said this gives them a shorter window of opportunity to convey the disadvantages of unionizing to their employees. The NLRB rule streamlines the unionization process and defers most eligibility determinations until after votes have been cast.

The judge is expected to issue a final ruling by May 15.