UKIP's modus operandi is to leave the EU. Their main gripe with the EU is open door immigration. They adopt anti-immigration rhetoric to further their cause. As a result, their core support is made up of people who are anti-immigration.
It's hardly a controversial post.
You know exactly what you're saying though. 'Rhetoric' is often used as a pejorative term, and you're insinuating that a) being anti-immigration is a bad thing and b) that UKIP uses 'rhetoric' to win over voters