S President Trump administration asked the Supreme Court to allow mail-in ballot restrictions, according to WaPo

The mechanism here is not the merits of mail-in voting but the precedent of the administration seeking to alter ballot administration through the courts, which in past episodes has fed the risk premium attached to the certainty and timing of the result rather than to the identity of the winner. Court interventions of this kind have a track record of compressing timelines late in the cycle, with the practical effect concentrated in a small number of states where ballot deadlines and counting rules determine when a result can be certified. The questions that matter are scope, whether the Court takes the case and on what timetable, and whether it produces a merits ruling or a procedural holding that leaves the underlying rules in flux. Follow-ons worth noting are state-level litigation in parallel, any guidance on counting deadlines, and the reaction in longer-dated implied volatility and the dollar, where election-uncertainty premia have historically expressed themselves. Until the Court signals interest, this sits in the category of headline flow rather than a tradeable shift in probabilities.