Michigan unions, including the United Auto Workers, say that they are pushing for a November ballot measure that would amend the state constitution. The amendment would stop any right to work laws from being passed in Michigan. To get a measure on the ballot, the unions will need to collect about 250,000 signatures. The UAW says that they are trying to send a message to others about the rights of workers.
See "Unions to push to block 'right to work' in Michigan", David Shepardson, Detroit News, March 1, 2012