I truly think it’s an enormous error to think you could win this issue by simply shooting a nice thing louder than other people shout the loud thing.

They don't necessarily have to say nice things (and maybe you're right that they shouldn't). But they need to say something that is different, and preferably something that they can win on.

The problem is that there are two things getting conflated - border security (drugs, organized crime, terrorism) and immigration. I think the vast majority of the public is concerned really only with the former, but that gets seen as tacit support for draconian immigration policies.