The ones who espouse very similar ideas but wear suits have quite a bit more sway. In Belgium, they have enough support to tangle politics at the national level. In Fraqnce, Le Pen came within inches of the presidency. In the Netherlands, even though it comes in a peculiar form of populism, both Fortuyn and Wilders had enough influence to steer national level politics as well. In Italy, the resurrected fascist party has been part of almost all Berlusconi governments.

The only limiting factor on most of these is that they tend to be personal cults. I.e. if the leader quits or falls in disgrace, they tend to crumble.