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The U.S. Supreme Court declined Tuesday to rehear a challenge to the power of public sector unions.

Without comment, the court issued a one-line order saying it would not put the case back on the docket for next term.

In March, the court reached a 4-4 tie in a case brought by a group of California teachers. They challenged the requirement that public employees who don't want to join a union must still pay a share of union dues, to cover the cost of negotiating contracts.

Related: Supreme Court Tie Spells Win for Unions in Fee Case

The tie vote left a lower court ruling, in favor of the unions, in place. The outcome was a big boost for unions representing millions of the nation's public employees — teachers, firefighters, nurses, and police — in nearly half the states.

The challengers seemed certain to win when the case was argued in January, but the death a month later of Justice Antonin Scalia removed the likely fifth vote they needed in order to prevail.

By seeking rehearing, the challenges were hoping the court would take up the issue again next term after a ninth justice was confirmed. But the Supreme Court almost never grants requests to hear a case again.