Sure, you could work as a lobbyist or a government affairs officer even though you aren't a citizen. You would just need to study US politics and policies. Then find a company that is willing to sponsor you for a Visa. The other option would be to do your graduate work here or study abroad here and see if you can parlay that into some interning/volunteer experience to really get your foot in the door. The other thing that I would do if I were you would be to look at international companies that have representation in the EU and here in the US. That way you can see about working for them and maybe doing an exchange within the company. There are ways you will just have to get creative.