The political argument has never been about having a secure border that will stop all the drugs and criminals, it's really about stopping anyone who wants to come here from just being allowed to walk right in without even being checked.
If Democrats had their way right now they would welcome EVERYONE in the current caravan, without even making them stop and identify themselves. They have done everything they can to prevent Republicans from being able to stop them at the border. Their mantra is that the few tiny number who might be criminals or terrorists are not a sufficient excuse to deny the tens of thousands who are not, "THEIR RIGHT" to immigrate to the US. They believe everyone in the world has the right to live in the US if they want to. They believe even the poorest and most unhealthy immigrants pay taxes when they get to the US, and do work that American Citizens won't do but need done. They point at the Statue of Liberty, ask us to re-read the quote, "give us your poor your tired your huddled masses".
If Republicans had their way right now they would build a border and enforce all our existing immigration laws. They talk about drugs, criminals and terrorists a lot but know those are a tiny minority of the millions who want to come to the US. They also know the numbers and the vast majority of Illegal Immigrants are dirt poor and will need to be highly subsidized with tax money in order to provide them with basic educational and medical services, and food and housing that meets US standards. They hesitate to confront large corporations who increase their own profit margins by paying them low wages counting on the fact that they and their families are otherwise being subsidized with tax money.
Yes, Republicans know its true, the average poor immigrant his a huge revenue loss for the US, but Democrats argue that we're a rich country and can afford it even thought Republicans remind them we are borrowing money every year because as a country we spend more than we take in in taxes.
I do wish we could put an end to this by allowing the Democrats and all their supporters to sponsor all the immigrants they want with THEIR OWN MONEY. If they want to bring millions of poor people here just offer to pay whatever difference it costs, and that would take the Republicans biggest rational argument right off the table.