JEFFERSON CITY, Mo. (AP) -- Missouri voters were deciding Tuesday whether to implement a right-to-work law limiting labor union powers that had been passed more than a year ago by Republican state officials but placed on hold when labor groups petitioned to force a public referendum.
If voters consent, Missouri would become the 28th state outlawing mandatory union fees in workplace contracts and the sixth Republican-led state to do so in the past six years.
National and local labor unions have spent millions of dollars trying to defeat Proposition A, hoping to turn around a recent trend that has diminished their powers in several historic union strongholds.
The referendum marks the first chance for the public to weigh in on union powers since the U.S. Supreme Court ruled in late June that public sector employees cannot be compelled to pay fees to unions. Missouri's ballot measure would essentially extend that to all private sector employees in the state.
At issue are so-called fair-share fees, which are less than full dues but are intended to cover unions' nonpolitical costs such as collective bargaining. Unions say it's fair for people to pay the fees, because federal law requires them to represent even those employees who don't join. But supporters of right-to-work laws counter that people should have the right to accept a job without being required to pay a union.
Former Missouri Gov. Eric Greitens signed a right-to-work bill passed by the Republican-led Legislature in February 2017. It was set to take effect as law on Aug. 28. But before that could happen, union organizers submitted enough petition signatures to suspend its implementation pending a statewide referendum.
A "Yes" vote Tuesday would allow the law to take effect. A "No" vote would permanently block it.
Advertisements about the ballot measure generally have focused on economics, with supporters claiming that right-to-work policies lead to more jobs and opponents claiming that they drive down wages.
Studies have found mixed and sometimes conflicting results.
The Washington-based Economic Policy Institute, which opposes right to work, found that wages in right-to-work states average 3.1 percent less than elsewhere after accounting for other workforce differences such as educational backgrounds, racial composition, the industrial makeup of employers and the cost of living.
But a case study focused on Oklahoma found different results. Economists Ozkan Eren of Louisiana State University and Serkan Ozbeklik of Claremont McKenna College in California used data from states with similar characteristics to analyze the effect of Oklahoma's 2001 right-to-work law. They found it resulted in a significant reduction in private sector unionization rates but had no short-term effect on either the total unemployment rate or average private sector wages.
Most right-to-work laws were enacted in the 1940s and 1950s. But Republicans have led a resurgence of such laws, starting in Indiana in 2012 and following in Michigan, Wisconsin, West Virginia and Kentucky.
Union membership in Missouri stood at 8.7 percent of the workforce last year, compared to 10.7 percent nationally, according to the U.S. Bureau of Labor Statistics. Nationwide union membership rates have been steadily falling for decades and are now less than half of what they were in 1978, when Missouri voters last defeated a right-to-work proposal.