I think it's going to become a bigger problem in Europe than the US. Despite (or perhaps because of) having immigrants from all over the world, a stranger-hostile party has never received any significant power in the US. The British National Party has a couple of seats in the European parliament, Dutch PVV too. We have a nationalist party in Sweden which is similar to these parties and its gaining more and more ground. The best thing to do would be to switch to a first past the post system like in Britain to exclude these kind of parties from a national level.