All kidding aside. There aint a GD thing gonna be done to him even if he is found out. The strongest thing I could see happening is him resigning in disgrace and then getting a pardon from Ol Joe, like Ford did for Nixon.
The best thing would be for the Congress demand he get the hell out of the country and take away his citizenship. Then, what ever happens to him after, happens. Get my drift?
You make the false assumption he is a citizen. Just kick his ass out. He has yet to prove citizenship.