I am a self-employed political consultant and would like to hire a non-US citizen to help me work on EU-US relations and have him work with me in the US. I am confident that his expertise cannot be matched by what's on offer on the local market (visa requirements), but I was wondering if anyone had gone through this or could provide any additions tips? I have done searches on this, but I seem to run into a lot of stuff that focuses on central Americans coming to the US or IT contractors doing temporary jobs.
The issue is working inside the US - this requires a work visa plus you would be dealing with a traditional employee relationship. A good alternative is to start working with the person remotely. This works very well if you are disciplined and have a decent HD video setup (Skype); I've been practicing this for years with very good results.
In this setup, his work is then 'produced' outside the US (as a foreign contractor) and therefore subject to taxation in the country of residence (where he already knows the applicable laws for freelancing). Let him simply bill you on a monthly or biweekly base. Business visits, where you can collaborate in one location are usually not a problem - if they are not excessive (more details about what constitutes a hidden employment relationship are at the IRS / Dept. of Homeland Security websites).
Once you feel that you really need to have the person local, you can start the process of getting a work visa. This will take time, money and definitely requires a qualified attorney.