The fight for a higher minimum wage has become a hallmark of the progressive left as it seeks to take back power from Republicans, at both the state and federal levels. Support for Fight for $15 has practically become a litmus test for aspiring Democratic politicians. But nearly a year after Republicans extended their domination of statehouses across the country, a new challenge has emerged: preventing Republicans from lowering the minimum wage in cities that have voted for a wage hike.

At the end of this week, Eric Greitens, the Republican governor of Missouri, is set to let a minimum wage preemption bill go forward without his signature, which would cause workers in St. Louis to lose a raise hike that went into effect in May. (The Missouri constitution sets a deadline for bills to go into effect even if the governor takes no action.) He has rejected calls to veto the bill, meaning the minimum will drop from $10 an hour to the state wage of $7.70. The state government, which became a GOP trifecta in the 2016 election after Greitens replaced Democratic Governor Jay Nixon and Republicans consolidated their control of the Senate and Assembly, will be taking money straight out of the pockets of an estimated 35,000 workers.

In recent years, the fight for a higher minimum wage in St. Louis, a city with a large population of African-Americans, has largely been waged between the state legislature and the courts. In 2015, the city passed an ordinance that would ultimately increase wages to $11 per hour. That was held up in court for two years after a consortium of business groups sued to block the raise. In February of this year, the Missouri Supreme Court unanimously voted to uphold the wage increase, but it was stalled again after opponents filed for a rehearing.

In April, the state Supreme Court declined to reconsider the ruling. And finally, on May 5, a new $10 minimum wage went into effect. In January 2018, that floor was scheduled to rise again to $11. The back-and-forth, however, was not without its costs. In addition to creating intense uncertainty for workers, the hold-up had a real-world impact: the National Employment Law Project estimates that it cost workers at least $35 million in overdue wages.