Indiana Gov. Mitch Daniels signed a controversial “right to work” law this month, making Indiana the 23rd state and the first state in the Rust Belt of the industrial Midwest and Northeast to adopt such a measure. The law, which bans union contracts that require fees from nonmembers, spurred protests from thousands of union members and could affect upcoming elections in Indiana and similar measures in other states, according to The Indianapolis Star.

The Republican-controlled Indiana state legislature approved the bill over Democrats’ objections. Supporters say the measure will encourage new employers to locate in the state, but opponents say there is no evidence that it will lead to more Indiana jobs. Both sides say they will make passage of the law an issue in state legislative races in November.

Indiana’s action could be significant for other states. Previously, no state had adopted a “right to work” provision since Oklahoma in 2001, according to the newspaper. Twelve states considered but did not pass such measures in 2011.

New Hampshire’s legislature last year failed to override the governor’s veto of a “right to work” measure. Supporters hope to revive the issue there this year. In Ohio, this month supporters got approval of the state attorney general to attempt a “right to work” ballot initiative. Other states that could consider similar measures include Kentucky, Maine, Michigan and Montana.

Union leaders say “right to work” laws lower living standards and working conditions for union and nonunion members. Supporters say the measures ensure fairness and create jobs. The fight in Indiana could be crucial for both sides.

“We’re hoping that showing that this can be done in a state like Indiana is going to bring other states around,” Patrick Semmens, a spokesman for the Virginia-based National Right to Work Committee, told the Star.