But it's not just about Trump. It's also about Senate and House Republicans. They don't share Trump's seeming invincibility. They might be primaried if they support DACA. That's why a deal on DACA might be a good thing to do and should not be seen as conceding something for nothing.
The modern-day GOP never, ever trades anything away that it wants. If they allow DACA to form part of a deal then they wanted it in the first place.
The GOP process seems to be as follows:
The Democrats want 1, the GOP wants 5. After a certain amount of wrangling a temporary solution based on 3 is the result.
When the time comes to re-negotiate the GOP squeals about how it was so unfair last time and how the Democrats always get their way so the new position is that the Democrats want 2, or maybe even just the status-quo but now the GOP position is that they want 8, another temporary solution of 5 is agreed.
Finally things come to a head and a permanent solution has to be found. The Democratic position is now 3 or 4 but the GOP position is now 10 - their justification being that they had to compromise so much the last two times. Eventually the Democratic Party gives some huge concession on some other subject to fix the final position on 6 and the GOP make such a big deal over how much ground they gave from their 10 position.
The Democrats claim a huge victory and justify giving up so much other stuff because they got more of their way in the final negotiation. What they fail to notice is that the end point is more than the GOP ever wanted in the first place.
I'm despondently confident that whatever permanent position the US ends up with w.r.t. DACA is something the GOP would have been very happy with at the outset and in the process they will have got funding for the wall, all kinds of concessions over immigration and a host of other things in the bargain. It's the way they roll and it has nothing to do with President Trump's deal-making and everything to do with the GOP's willingness to keep moving the goalposts until they get what they want.
