We have guest worker programs already.

Sort of. The employer has to petition the specific worker. It's an H2A (for ag workers). That is very tricky to do, in practice (even if it's fine in theory).

We have never had open borders, at least not since I was old enough to vote. Obama deported huge numbers of illegal migrants. Albaby repeatedly provided statistics and data that indicated there was no dip in removals. It's simply a myth.

There are some fringe-left people that support open borders. But they are not significant in terms of voting power. There are a large number of supporters for the DREAMERs, and similar. But that's not really the same thing. I think I can safely say that the left (realizing the left is not a monolith) doesn't want "illegals" any more than the right does. We simply want a workable guest worker (bracero) program, fair dealing with DREAMERs, and a generally more humane system. Then we will have a lot less stress on the system, and we will know exactly who is here and where they are.