Michigan's largest teachers' union says fewer than 5,000 school employees, or less than 5 percent, resigned their membership during a window last month.
The Michigan Education Association made the figure public Thursday after an administrative law judge said members should be able to resign anytime. The lobbying of members by conservative groups and union leaders has been watched as a key first test of a right-to-work law.
About 1,500 MEA members left in August 2013. And up to 5,000 opted out last month.
That's about 6 percent of 112,000 active members in the union last year.
MEA President Steve Cook says members stood strong against "outside rhetoric" and are committed to the union. The free-market Mackinac Center, however, notes that 50,000 members aren't eligible to leave until contracts expire.