This is the easy way:

Foreigners come to country ->

Foreigners need jobs ->

Foreigners get jobs ->

Less jobs for nationals.

That's a very easy reasoning to following, it also gathers a lot of popularity, specially if I'm out of a job o with one I don't like.

Explaining why this is not true, or rather why it is much more complex than that, takes a lot of time, effort and understanding of non trivial economic concepts.

I would say the later is the hard way, this kind of reasoning applies to so many things that said by politicians all around the world to gather votes.

I would also like to clarify that I absolutely don't believe that that kind of reasoning is only used by the right wing politicians, that would be extremely naive.