WASHINGTON: The Supreme Court is poised to deal a sharp blow to the unions that represent millions of teachers and other public employees, announcing Thursday it will consider striking down the mandatory fees that support collective bargaining.

The justices will hear the case of Mark Janus, an Illinois state employee who objects to paying fees to the union, which represents 35,000 state workers.

The decision, due by next June, could prove a costly setback for public-sector unions in 22 states, where such fees are authorized by law. Labor experts have predicted a significant percentage of employees would stop supporting their union if given a choice. The other 28 states have “right to work” laws that forbid requiring workers to join or support a union.

With smaller numbers, public employee unions would lose some of the political power that has made them major forces in some states, such as California, Illinois and New York.

The nation’s four largest public-sector unions — the National Education Association, the American Federation of Teachers, the Service Employees International Union and the American Federation of State, County and Municipal Employees — sharply criticized the case, calling it “a blatantly political and well-funded plot to use the highest court in the land to further rig the economic rules against everyday working people.”

“These powerful interests want to gut one of the latest remaining checks on their control — a strong and united labor movement that fights for equity and opportunity for all, not just the privileged few,” AFT President Randy Weingarten said.

The unions have had time to prepare for what’s coming.

Early last year, the court’s conservatives were poised to strike down these so-called “fair share” fees in a suit brought by a California schoolteacher. But Justice Antonin Scalia died unexpectedly in February, leaving the court split 4-4 and unable to decide the case of Friedrichs vs. the California Teachers Association.

Now, the court has agreed to hear a new case presenting the same issue. And this time, Justice Neil M. Gorsuch can — and most likely will — supply the fifth vote for a conservative ruling.

On Thursday, Gorsuch drew protesters to the Trump International Hotel when he gave a speech to a conservative education group.

Several progressive groups accused Gorsuch of undercutting the court’s appearance of impartiality. They said he may be required to recuse himself if the justices are asked to decide whether Trump is violating the Constitution’s ban on presidents taking an emolument from a foreign state — as critics have suggested he is — by profiting from foreign emissaries using the hotel.

Groups, including Planned Parenthood Federation, sent a public letter to Chief Justice John G. Roberts Jr.