That dilemma stems from newly proposed USPS rules that seek to comply with an executive order President Donald Trump signed this spring to crack down on mail-in voting. If courts let the order stand, it would give the federal government an unprecedented role in elections — and could put even more voter data in the hands of Trump officials searching for supposed election fraud.



The Wikipedia synopsis is pretty accurate for what happened:
https://en.wikipedia.org/wiki/Oshkosh_NGDV#Changes_to_battery-electric_drivetrain_proportion