The justices divided 4-4 in a case that considered whether public employees represented by a union can be required to pay "fair share" fees covering collective bargaining costs even if they are not members.
Big business and labor both support legislation that would let companies cut workers' hours during downturns but let the employees collect partial unemployment. But Gov. Mike Pence's administration says it would be expensive to implement and so the bill will die.
Five of the nine justices hinted that they were poised to let government workers refuse to fund the cost of collective bargaining. That step would be a blow to public-sector unions, which account for almost half the country's unionized workers.
Republic Airways Holdings Inc. announced Tuesday that a majority of its 2,100 pilots have approved a new three-year contract, ending a years-long labor dispute that threatened to put the regional airline out of business.