ST. PAUL, Minn. – Fifteen months after taking control of Minnesota’s Legislature, Republicans have put a gay marriage ban on this November’s ballot, moved to expand gun rights and cast dozens of votes to cut state spending. But there’s one issue where they failed to get traction: watering down the strength of organized labor with a right-to-work law.

The problem isn’t so much opposition from Democrats. And it isn’t a lack of enthusiasm for the idea, which many conservatives consider essential for creating a business-friendly economic climate. The problem lies with Republicans who fear triggering a huge rebellion among opposition labor unions and sending a surge of sympathetic voters to the polls in November to vote Democratic.

In Minnesota and elsewhere across the Midwest, the question of what to do about the right-to-work issue is pitting Republican against Republican, straining relationships among longtime allies and weighing cherished ideals against political tactics.

“We wait and we wait and we wait, and then if we get the opportunity and we fail to take it, then the issue is done,” said Michelle Benson, a frustrated Republican state senator from suburban Minneapolis who sounded off after House and Senate leaders’ recently decided not to move on the issue.

The passage of a right-to-work measure in Indiana this year emboldened supporters in Minnesota, Michigan, Ohio, Wisconsin and Missouri to try to carry the initiative across the Rust Belt. But many GOP leaders were instead more impressed by the furor that the unions kicked up in defeat. Throngs of protesters mobbed the state capitol in Indianapolis and Democratic lawmakers periodically disrupted the legislative session with boycotts. Huge demonstrations also came after Wisconsin Republicans stripped public employees of collective bargaining rights last year.

“Whether you agree with right-to-work or not, you’ve got to agree there’ll be millions of dollars coming in from other states, and thousands of people,” said Minnesota state Rep. Tony Cornish, a Republican who opposes trying to pass a bill. “Buses emptying out, banners, people camping.”

The Minnesota proposal had one committee hearing last month – provoking a labor protest and AFL-CIO sponsored TV ads. Although union membership has declined nationally in recent decades, organized labor remains a political force in Minnesota, with the AFL-CIO boasting about 300,000 members. A big Democratic turnout this November could make it more difficult for Minnesota’s GOP to defend the more than 30 state House and Senate seats they seized from Democrats in the 2010 election.

But some conservatives respond with another question: If not now, when? Republicans hold more legislative sway in the Midwest than they have in years as a result of that 2010 landslide. Their ability to pass right to work might never be greater, especially if they lose seats this November.

The GOP’s tea party flank also tends to favor action. Last weekend, Benson triumphed in a party endorsement battle with fellow Republican Sen. Mike Jungbauer, a right-to-work skeptic.

For many conservatives, it’s a deeply felt goal. When Steve Drazkowski began serving in the Minnesota House in 2007, Democrats had controlled at least one chamber of the legislature for a full generation. “Four decades, right there,” in which they couldn’t achieve their policy goals, Drazkowski said.

After Republicans finally won control in 2010, he put right-to-work state at the top of his to-do list.

His measure, which would preclude unions from collecting dues from workers in union shops who did not want to be union members, would make Minnesota a more attractive place for people to work and businesses to locate, he said. Opponents argue that workers who benefit from the better wages and workplace conditions that unions negotiate should share the costs.

The Minnesota measure would actually be a constitutional amendment that would go before voters – a necessity to get around a certain veto from Democratic Gov. Mark Dayton. But now it is moot.

GOP leaders also fear the political consequences of right-to-work in Ohio and Wisconsin, where the presidential race could be close and where Republicans will also be defending legislative majorities.

In Wisconsin, where GOP Gov. Scott Walker faces a recall election in June as the result of last year’s anti-union legislation, Republicans did nothing with right-to-work this year.

In Ohio, a coalition that includes some tea party groups is collecting signatures to get a right-to-work amendment on the statewide ballot but Republican Gov. John Kasich has publicly dismissed the effort. In Michigan, Republican House Speaker Jase Bolger has been leaning toward supporting a right-to-work measure, but Republican Gov. Rick Snyder has said he wants no part of it.

“Right-to-work is such a divisive issue,” said Amber McCann, a spokeswoman for GOP Senate Majority Leader Randy Richardville, who has said he would consider Senate passage unlikely.