TIS, there is a ton of precedent regarding this. It would be so easy for the Solicitor General to simply have a federal judge quash the state subpoena. However, the more expedient course would be for the president to ignore it. There are so many issues involved. The first one that comes to mind is the Georgia citizen's standing to even have their complaint considered. Of course, a default judgement by the court would certainly be challenged by Georgia's Secretary of State and the Georgia Democratic Party.