On June 2, the U.S. Supreme Court revealed that on May 29, it had decided to hear Bost v Illinois State Board of Elections, 24-568. The original issue in the case had been a challenge to the 2005 Illinois law that allowed postal ballots to be counted if they had been received after election day, but had been postmarked by election day. The lower federal courts had held that the plaintiffs, who were Republican Party nominees for U.S. House and presidential elector, did not have standing to challenge the law. Here is the cert petition.
The plaintiffs are only asking the U.S. Supreme Court to rule that candidates do have standing to challenge election laws; they are not asking the Court to decide the original issue of whether states can count ballots that arrive after election day. Assuming the Court rules in favor of standing for candidates, that would be helpful to plaintiffs in many types of election law lawsuits.