In The Netherlands Geert Wilders' PVV became the second party by size, but the rest of the mainstream parties refuse to form a coalition with them so they are pretty much always in the opposition. I don't like that type of party (we had the LPF, then PVV and in the future maybe FvD) but I have to admit that as long as they don't actually govern they have a very useful function in that they often point out painful truths or situations that the other parties won't touch for fear of seeming politically incorrect.