I want to throw out a quick tactic in rhetoric for this particular line because it is so common but is often bungled by comrades online and in real life and the counter is easy. Allow me to illustrate through a hypothetical conversation between a comrade (C) and a liberal (L):
L: I don't hate immigrants, I'm against ILLEGAL immigration.
C: Okay, what if I could pass one law that would get rid of all illegal immigration overnight and there would be no more in the future ever again. Once you hear it you'll understand exactly why illegal immigration could be eliminated this way. Would you support it?
L: Sure, sounds great.
C: I would make ALL immigration legal. Every immigrant would from now and forevermore be automatically approved and put through the process to longer term residency or citizenship status.
Posing your fix to immigration like this immediately exposes the lie that they don't hate immigrants. The next sentences out of their mouths will be why some immigrants are not worthy or how this is unthinkable (even though it has been the norm for 99.9% of human history). It's such an easy retort. It's leftist. It jumps right into the contradiction their ideology holds.
Now of course they will try and dig into details but it's important not to ever get bogged down in details of how such a policy would work. Of course, as a mental exercise for yourself it might be fun to think about but the details of the policy are irrelevant. The point here is they hate ILLEGAL immigrants. You can propose to get rid of the ILLEGAL parts. Would they welcome all immigrants who are LEGAL? No, of course they will not. It is important to keep reiterating, "but they will be legal and those are the immigrants you like."
As with all rhetorical tools it will not convince most people. The goal with using rhetoric and responding to rhetoric is often not to convince the person you are interacting with. It is to put them in an uncomfortable position while appealing to an audience.
I like this one because it plays into everything most liberals and even many conservatives don't want to admit: their anti-immigration ideology is racist and they can try and hide behind the law all they like but they cannot once that shield is stripped from them. Of course, that means that this kind of rhetorical retort is useful in for some other policies as well. I often like to propose legalization when someone says they don't like the ILLEGAL aspect of something. They are almost always using that to shield racism, classism, or some other form of sociological bigotry.
Hope this helps.