Justin Sullivan via Getty Images Fast-food workers in St. Louis could see their wages go backwards, after state Republicans nullified the city's new minimum wage.

Two months ago, Cynthia Sanders got a raise at her janitorial job, from $8.30 to $10 per hour, after St. Louis passed a law raising its minimum wage. The extra money has helped the 51-year-old cover groceries and utilities as she raises three grandchildren.

But in just a few weeks, Sanders’ pay rate could drop back down again, thanks to a new law Republicans in the Missouri legislature passed invalidating St. Louis’ minimum wage.

“It was life-changing to get this, and it’s going to be life-changing to have it taken away,” said Sanders, who cleans four kitchenettes and eight bathrooms per shift at a Wells Fargo building downtown. “You’ve got children looking at you to be a provider. How do I tell them we’ve got to eat noodles again this week?”

Like other low-wage workers in Missouri and beyond, Sanders finds herself caught in a political and legal battle between local Democrats and state Republicans. As blue cities become incubators for progressive policy, their red state legislatures are trying to thwart them through “preemption laws” that forbid cities and counties from implementing their own measures related to the minimum wage, paid sick days, plastic bag taxes and other hot-button issues.

So far, Republican state legislators are winning the fight. In Missouri, for example, the GOP controls both chambers of the statehouse as well as the governor’s mansion.

It was life-changing to get this, and it's going to be life-changing to have it taken away. Cynthia Sanders, St. Louis janitor

Under the law Republicans passed in response to St. Louis’ new ordinance, no locality could have a minimum wage higher than the state level of $7.70 per hour. And St. Louis is not the only city immediately affected. A referendum to gradually raise the minimum wage in Kansas City to $15 was slated to go on the ballot in August. Gov. Eric Greitens (R) said he does not intend to veto the bill. So under the rules of the Missouri Constitution it will eventually go into effect automatically, reverting the St. Louis minimum wage to $7.70 on Aug. 28. It would also preempt the minimum wage under consideration in Kansas City.

While preemption laws have been around for years, Republicans are increasingly turning to them to nullify local liberal policies. According to a February report from the National League of Cities, 24 states now block local minimum wage hikes, 17 block local paid leave mandates, and three block local anti-discrimination measures. The group attributes the growing use of preemption laws to the fact that Republicans now have 25 so-called state government “trifectas” ― control of both legislative chambers and the governor’s office.

The laws have become a particularly effective tool for blunting the “Fight for $15” campaign, a union-funded initiative aimed at raising the minimum wage and unionizing low-wage workers. While the federal minimum wage has remained $7.25 since 2009, voters and city halls have embraced proposals to raise the local minimum wage, in some cases hiking the wage floor to as high as $15. (The federal minimum wage prevails anywhere local law does not mandate a higher one.) The preemption laws have provided Republican state officials with a way to block proposals that poll extremely well and have strong financial backing from unions.

Jim Young / Reuters Fast-food workers with the "Fight for $15" campaign have demanded a $15 minimum wage and union representation.

Dennis Shaw, who works at the St. Louis grocery chain Schnucks, received a $1.70 raise due to the St. Louis ordinance. The pay bump translated into an extra $30 or so each week after taxes ― a welcome addition that has helped him pay rent on his one-bedroom apartment downtown and avoid bank overdraft fees. He said that legislators in the state Capitol don’t understand what it’s like for someone trying to survive on the minimum wage in the city.

“It borders on disgraceful,” Shaw, 36, said of the preemption law. “This isn’t just not getting a raise ― it’s a pay cut. It will result in bills not being paid.” Shaw’s union, the United Food and Commercial Workers, estimates that 500 of its members in the city could see their pay downgraded in August, according to a spokesman.

Republicans who have pursued preemption laws have often argued that they want to avoid a patchwork of minimum wages around the state, which they claim could be confusing for employers. But Rep. Jason Chipman, a Republican who represents a rural district southwest of St. Louis, said he sponsored the measure in the Missouri House of Representatives because he didn’t think the government should dictate minimum wages to employers.

“The government is not here to run people’s businesses,” Chipman said in an interview, arguing that higher minimum wages kill jobs. “If an employee doesn’t like what’s being offered, they can go somewhere else. Be more productive. Be worth more.”

“These are supposed to be entry-level jobs,” he added. “We understand there are people who rely on these jobs who are not entry-level-type people, but you can’t legislate by the exception.”

Craig Barritt via Getty Images Gov. Eric Greitens

One of the prime grievances lobbed against preemption laws is that they undermine local governance. It’s an odd look for Republican legislators who often rail against meddling in parochial affairs by Washington. Asked why St. Louis or Kansas City shouldn’t be able to determine its own policies ― even if those policies are folly ― Chipman said the cities are economic drivers that impact the whole state. “When you lose economic output, you lose revenue to the state,” he said. “It doesn’t happen in a vacuum.”

Many of the preemption battles are tinged with a racial component, as mostly white legislatures override the laws of heavily minority cities. (St. Louis has a black plurality, and the minimum wage raise would disproportionately affect minorities.) In Alabama, the overwhelmingly African-American city of Birmingham also raised its minimum wage to $10.10, only to have the majority-white legislature block it with a preemption law. The Alabama chapter of the NAACP filed a civil rights lawsuit, which was thrown out by a judge but is now on appeal.

Many of the preemption battles are tinged with a racial component, as mostly white legislatures override the laws of heavily minority cities.

The Missouri law presents an unusual case because so many workers in St. Louis have already received raises. Chipman said he had hoped to avoid such a situation, blaming the state Senate for not moving quickly enough to pass the preemption law before the St. Louis ordinance went into effect. Greitens, too, chided the state Senate for not fast-tracking a bill, providing that as the reason he would not put his signature on it. Missouri Democrats have called Greitens’ passive approval of the law craven.

Nick Desideri, a spokesman for the Service Employees International Union Local 1, said he still holds out hope that Greitens will veto the preemption measure, given the optics in St. Louis.

“The level of cruelty in this thing just boggles my mind,” said Desideri, whose union has been the primary backer of the “Fight for $15.”

The St. Louis employers who doled out raises due to the short-lived minimum wage hike will soon have to decide whether or not to revoke them. Of course, workers don’t appreciate seeing their pay go backwards. A spokesman for Shaw’s employer, Schnucks, which has eight stores in St. Louis, said the company plans to revert to the pay rates laid out in the union contract.

That means Shaw’s pay would drop back to $8.30. Shaw said that he considers Schnucks a good employer, but he wouldn’t expect them to honor the higher rates once legislators give them an out.

“Businesses are not in business for moral obligations,” Shaw said. “I would hope they keep [the raises] in place, but I could imagine them taking them away. And I wouldn’t blame them should that happen. There are others I could blame.”