As protesters shouted "shame on you" from the gallery, Michigan's Republican-led House of Representatives on Tuesday passed a contentious "right-to-work" law by a vote of 58 to 51.
The law makes union membership and payment of dues voluntary for public sector workers such as teachers, the only government workers excluded would be police and fire unions.
A second bill applying "right-to-work" to the private sector in the state is expected to be debated and approved by the House later on Tuesday.
The Senate has already passed both bills. Gov. Rick Snyder has said he will sign the bills as early as Wednesday, which would make Michigan the 24th "right-to-work" state in the country.
Huge crowds of union backers massed on the grounds and in the state Capitol halls Tuesday morning, insisting the legislation would drive down wages and benefits.
Passage of "right-to-work" bills is a major blow to organized labor in the United States because Michigan, home to the large U.S. auto industry, is a stronghold of unions.
"These so-called right-to-work laws, they don't have anything to do with economics, they have everything to do with politics," Obama told cheering workers Monday during a visit to an engine plant in Redford. "What they're really talking about is giving you the right to work for less money."
Programming note: The Ed Show blog is on the ground today with periodic reports from Lansing and The Ed Show will have complete coverage tonight at 8pET on msnbc. Ed's guests will include Andy Kroll of Mother Jones, Sen. Debbie Stabenow of Michigan and Mayor Virg Bernero of Lansing.