The Court decides in Moore v. Harper, just issued.
From the syllabus:
The Elections Clause does not vest exclusive and independent authority in state legislatures to set the rules regarding federal elections. Marbury v. Madison, 1 Cranch 137, famously proclaimed this Court’s authority to invalidate laws that violate the Federal Constitution. But Marbury did not invent the concept of judicial review. State courts had already begun to impose restraints on state legislatures, even before the Constitutional Convention, and the practice continued to mature during the founding era. James Madison extolled judicial review as one of the key virtues of a constitutional system, and the concept of judicial review was so entrenched by the time the Court decided Marbury that Chief Justice Marshall referred to it as one of society’s “fundamental principles.” Id., at 177.
The Elections Clause does not carve out an exception to that fundamental principle. When state legislatures prescribe the rules concerning federal elections, they remain subject to the ordinary exercise of state judicial review. Pp. 11–26.
That's the last opinion for today, per SCOTUSblog.
Chief Justice Roberts wrote the opinion, with Justice Thomas dissenting, joined in full by Justice Gorsuch and in part by Justice Alito.