After a succession of political setbacks in onetime strongholds and a landmark defeat in the Supreme Court, organized labor has notched a hard-won victory as Missouri voters overrode a legislative move to curb union power.
A measure on the ballot on Tuesday asked voters to pass judgment on a prospective law barring private-sector unions from collecting mandatory fees from workers who choose not to become members. The law was rejected by a 2-to-1 margin.
The Supreme Court in June struck down such fees for public-sector employees, achieving a longstanding goal of conservative groups and overruling a four-decade precedent.
Labor leaders argued that the rare opportunity for voters to weigh in directly on a so-called right-to-work measure — which several states have passed in recent years — revealed how little public support the policy has, at least once voters get beyond the anodyne branding.
“It shows how out of touch those institutions are,” said Richard Trumka, president of the A.F.L.-C.I.O. “How out of touch the Republican legislature in Missouri is, how out of touch the Supreme Court is.”
But Jake Rosenfeld, a sociologist who studies unions at Washington University in St. Louis, cautioned against overstating the victory. A mere 8.7 percent of workers in Missouri were union members last year, below the national average and down from more than 13 percent a decade-and-a-half ago.
“A ‘win’ just returns the situation to the status quo,” Mr. Rosenfeld said by email, though he acknowledged that it was “a huge morale boost to a beleaguered movement.”
The examples of Michigan and Indiana, where right-to-work laws took effect earlier this decade, suggest that the legislation could have cost unions thousands of members and millions in revenue.
One question is the extent to which the victory could reverberate beyond Missouri.
“I think this will build momentum and send a message to all legislators,” Mr. Trumka said, “that if you vote against the people, go against the will of the vast majority of working Americans, it’s going to cost you.”
But it was not immediately clear that the forces driving the impressive showing for labor in Missouri could be reproduced elsewhere.
One reason is that Republican voters who buck their party on a ballot measure, as many appeared to do in Missouri, may be unwilling to vote against Republican candidates in a general election, even when those candidates are hostile to labor.
“There’s a big difference between overturning the law itself and defeating legislators who supported it,” said Jonathon Prouty, a Missouri political consultant and former executive director of the state’s Republican Party. “It’s a lot easier for unions to energize their base around the issue, which is right to work, rather than against candidates.”
T. J. Berry, a Republican state representative whose district includes some outer suburbs of Kansas City, said that many of his constituents were proud union members who opposed right to work but nonetheless voted Republican because they were conservative on issues like abortion and guns.
“I have four guys who are Ford workers in my Sunday school class,” Mr. Berry said. “And they fit exactly what I’ve told you: Pro-life, pro-gun and pro-worker. All of them voted for Trump.”
Labor also appeared to enjoy a significant financial advantage in Missouri that is unlikely to recur in other states where Republicans have the wherewithal to pass right-to-work bills. According to state financial filings, the union-funded We Are Missouri coalition had spent just over $15 million on its ballot campaign as of late July, about three times what the four leading groups supporting the right-to-work legislation spent over the same period.
A key factor behind this disparity was the leadership vacuum that the former Republican governor, Eric Greitens, left when he resigned amid scandal in May.
“He was going to be the champion, then he was embroiled in controversy the whole year,” Mr. Berry said. “If you don’t have a leader, it’s pretty hard to rally the troops.”
Even so, Mr. Prouty acknowledged that the momentum against the right-to-work effort was more than a function of labor’s spending. “It’s like nothing I’ve ever seen,” he said. “There is energy out there.”
Mr. Greitens had signed a right-to-work bill into law after the legislature passed it in early 2017.
Supporters argued that the measure was essential to the state’s economic competitiveness.
“Companies that have a choice of expanding or choosing where they locate to begin with, they will generally choose — especially in the manufacturing sector — a right-to-work state,” said Daniel Mehan, president and chief executive of the Missouri Chamber of Commerce and Industry. He cited the manufacturing boom in the South in recent decades as a key data point.
But shortly after the law’s passage, unions and their allies in the state started a campaign to keep it from taking effect. They submitted about three times the roughly 100,000 required signatures by last August, setting up the statewide ballot vote, then began aggressively campaigning this spring for a “no” vote — that is, a reversal of the legislative move.
“I’ve been out knocking on doors, walking, since the middle of May,” said Mark Staffne, an electrical construction mechanic and union member, who lives in St. Charles County, which is heavily Republican.
“I met both Republican voters who voted for Trump and labor Democrats who voted for Trump,” he said. “By a vast majority, a huge amount of people I talked to said they’re voting no.”
Labor groups characterized right-to-work laws as an attack on workers’ livelihoods, because, they said, they undermine unions’ ability to negotiate wages and benefits. A 2015 report by the liberal Economic Policy Institute found that the typical full-time worker, not just the typical union member, earned about $1,500 per year more in states where mandatory union fees are allowed than in right-to-work states.
If union fees are not mandatory, workers can enjoy the benefits of union representation without having to chip in for unions’ work on their behalf, often known as the “free rider” problem.
These arguments appeared to resonate in Missouri, but Janice Fine, a professor of labor studies at Rutgers University, wondered whether the tendency of many unions to define their relationship with workers in narrow economic terms may be accelerating labor’s decline over the long run.
An overly transactional relationship might prove less compelling if workers feel they can spend their money better elsewhere — say, by joining a bowling league or a gym. The alternative would be to cultivate more of a philosophical commitment, making unions more akin to evangelical churches, albeit in the secular realm.
“I feel so ambivalent about that whole argument,” Ms. Fine said, referring to the free-rider case against right-to-work laws.
Any union that thought of itself primarily as providing benefits to members, she added, “had a very thin notion of what solidarity was.”
A version of this article appears in print on , on Page B6 of the New York edition with the headline: Voters in Missouri Reject Restrictions on Unions’ Power to Collect Fees. Order Reprints | Today’s Paper | Subscribe