Maine could become the latest U.S. state to thwart activist demands to hike minimum-wage rates, assuming Republican lawmakers get their way. The state Senate approved Thursday a bill that prohibits cities and towns from passing their own minimum-wage ordinances.

An Act To Promote Minimum Wage Consistency comes as some of Maine’s largest cities -- Bangor, Portland and South Portland -- consider lifting minimum pay above the current statewide floor of $7.50 per hour. Endorsed by Republican Gov. Paul LePage, the pre-emption bill moves to the Democratic-controlled state House of Representatives, where it faces an uphill battle.

Whether or not it passes, the proposal underlines the ongoing conservative counter-reaction to the success of locally focused campaigns to boost wages. Michigan, where Republicans control both legislative chambers and the governorship, is on its way to blocking municipalities from adopting nearly all labor standards that are greater than the state’s. Missouri legislators have already approved a proposal to rein in local control that now sits with Democratic Gov. Jay Nixon: Meanwhile, Kansas City and St. Louis are considering ambitious proposals to increase the hourly pay floor to $15. And, last year, as activists collected signatures for a wage-related ballot initiative in Oklahoma City, Oklahoma’s Republican Gov. Mary Fallin signed a pre-emption bill into law, effectively killing the campaign.

From state to state, a similar cast of characters backs the proposals: lobbying powerhouses such as chambers of commerce and restaurant associations joined by Republican legislators, frustrated by union-backed movements to raise pay that have managed to collect a string of impressive victories in cities such as Los Angeles and Seattle.

“If pre-emption were to pass, it would make things easier,” says Greg Dugal, CEO and president of the Maine Restaurant Association, which is also engaged in a more-local wage fight in Portland, the state’s largest city. “Our position is that wages should be set at the state or federal level.”

Dugal says national groups including the National Restaurant Association encouraged state Sen. Andre Cushing to introduce the pre-emption bill that passed Thursday. Although Dugal says the state’s restaurant operators would welcome such a law, he concedes it’s unlikely to pass this legislative session.

In a separate vote Thursday, the Maine Senate moved to increase the state minimum wage to $9 an hour by October 2018. However, that bill also included the pre-emption measure and rolled back some restrictions on child labor, making it unlikely to pass in its current form. Meanwhile, the state House of Representatives has voted for a $9.50 minimum wage by 2018.