In preparation for a Supreme Court decision that may deal a significant setback to public-sector unions, organized labor groups are launching new recruiting efforts as they mobilize for the midterm elections.

The case — brought by Illinois state worker Mark Janus against the American Federation of State, County and Municipal Employees — challenges existing law that allows government-employee unions to collect fees from nonmembers. The court could announce a decision as soon as Monday.

The AFL-CIO in recent days has started a nationwide advertising campaign, along with a companion website dubbed “Freedom to Join,” making a sales pitch for the perks of union membership. The ads are running in newspapers in nine states, including Michigan, Ohio and Pennsylvania, as well as in USA Today and The Washington Post.

“From the boardroom to the steps of the Supreme Court, a dark web of corporate interests is trying to stop us with everything it has,” reads the text of the ad from AFL-CIO President Richard Trumka. “But no matter what any CEO or lobbyist does, we’re standing up for the freedom to join together in a union.”

Catherine Fisk, a law professor at the University of California, Berkeley who specializes in labor matters, said the Janus decision may well cost unions in the 22 states, plus the District of Columbia, that allow organized labor to charge fees to every worker they represent, including nonmembers. It likely would result in a “substantial hit” to their budgets, leading to staff cuts, she said.

“Unions can avoid losing all this money if they can convince the workers they represent to join the union,” Fisk said. The advertising campaign is “no coincidence,” she added.

Unions have been anticipating a likely loss in the case ever since President Donald Trump won the White House in 2016. The court considered a nearly identical case earlier that year but deadlocked 4-4 because of the unfilled vacancy caused by Justice Antonin Scalia’s death.

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“It’s kind of interesting that the unions now are trying to appeal to the people who are agency fee payers to tell them why they should become full union members — which is something they should’ve done a very long time ago,” said union critic Rick Berman, executive director of the Center for Union Facts, a corporate-backed anti-union nonprofit organization. “They pretty much took people for granted. Now, they’re having to actually market themselves. … I think they’re going to have a difficult time.”

John Weber, a spokesman for the AFL-CIO, said union membership rose last year, according to Bureau of Labor Statistics data analyzed by the Economic Policy Institute, though union density remained about the same, with around 6.5 percent of the private-sector workforce and 34.4 percent of public employees.

The Janus case was part of a larger, decades-long effort to curb unions’ bargaining power and political influence, Weber said.

“Corporations are trying to fatten their margins at the expense of workers,” he said, adding that collective demonstrations have gained steam this year with teacher strikes in numerous states including Oklahoma. “Even as these CEOs and lobbyists are throwing everything they have at us, working people are putting on an enormous show of collective action.”

Younger workers, under the age of 35, accounted for nearly 200,000 of the 262,000 new union members in 2017, according to the Economic Policy Institute’s analysis.

“This is a powerful moment,” Weber said.

Political money chase

Though the court decision may have broad implications for the budgets of public-sector unions, it is unlikely it would cause an immediate hardship to labor’s political money coffers.

For one, political action committee money comes from voluntary donations.

“Unions already can’t spend money on politics except for money that they raise specifically to spend on politics,” Fisk said.

So far in the 2017-2018 election cycle, the AFL-CIO and its affiliates have donated about $470,000 to federal candidates and have invested a little more than $302,000 in outside political expenditures such as issue and political ads that are not done in coordination with candidates, according to the nonpartisan Center for Responsive Politics. Unions are well known for spending on get-out-the-vote campaigns for candidates and causes they support.

Based on past exit polling, labor organizations expect union households to make up about 20 percent of the electorate in the 2018 midterm elections, the AFL-CIO’s Weber said. Union turnout could be pivotal in battleground states such as Pennsylvania, where labor leaders say their member households helped propel moderate Democratic Rep. Conor Lamb into office during a special election.

Though political donations matter, of course, unions are stepping up their member-to-member persuasion efforts, Weber noted, with face-to-face conversations about what policy matters are at stake on health care and other issues.

“That’s the core of everything we’re going to do,” he said.

Even without a direct hit to union political dollars, Berman predicts that if the Supreme Court sides with Janus over the union, it will trickle into labor’s electioneering efforts.

“Their ability to be political animals, rather than collective bargaining institutions, clearly is affected,” he said. “Without as much money, they don’t have as much staff.”