It's hard to argue against the answer being Golden Dawn, with Jobbik maybe not far behind.
With a stricter definition of "major party", I'm very tempted to say the Republicans, but there are some other convincing candidates mentioned in this thread, such as Fidesz and Berlusconi's lot. I'd also suggest that the Swiss People's Party deserve a mention.
Fidesz is definitely worse than the GOP, but only by a depressingly small amount. Then again, I don't think Fidesz has ever intentionally damaged Hungary's credit rating as a bargaining tactic to force cuts in welfare for poor people to fund tax cuts for the extremely wealthy.
