The parties' basic calculations run as follows.
Republicans want to force Democrats to pass a spending bill without any protections for the Dreamers, because Republicans would have more leverage to extract more hardline immigration concessions if the vote on the Dreamers does happen later, decoupled from the government funding dispute.
Democrats don't want to forgo this leverage - without the government funding at stake, there is less pressure on Republicans to even hold such a vote.
But at the end of the day, Trump and Republicans will either have to protect the Dreamers, or decide not to. And this will settle the question of how they fundamentally view these people.
As it is, Trump's vacillation on the Dreamers is a major cause of the shutdown. Trump was first warm to, but later rejected, the original bipartisan deal that would have protected the Dreamers, because his hardline advisers talked him into believing he wasn't getting enough immigration concessions.
Then Chuck Schumer signalled openness to giving Trump his border wall, and they were close to another compromise, but Stephen Miller and John Kelly intervened. GOP Congressional leaders also helped scuttle it.
There are two ways to interpret this. Either Trump's hardline advisers and/or GOP leaders don't actually want any deal that protects the Dreamers, or they do want one eventually and hope to maximise leverage to extract more of what they want later.
But either way, the bottom line is that the right wing is vetoing the current bipartisan compromise effort. And Trump cannot decide what price would make protecting the Dreamers worth his while, which is why he keeps getting manipulated into backing off from compromises.
At the core of this is a deeper vacillation - about who the Dreamers really are. Trump and GOP leaders have in the past repeatedly cast the Dreamers as morally blameless for their plight and have vowed to enable them to continue making positive contributions to American life. House Speaker Paul Ryan did just this in a year-old dramatic exchange with a dreamer mother.
Yet Trump and Republicans have pivoted to falsifying the real cause of the shutdown by bashing Democrats for closing down the government to protect "illegal immigrants".
This is a dramatic swing towards portraying Dreamers as nothing more than lawbreakers - toward lumping in the Dreamers with the broader undocumented population, which Trump has tarred with all kinds of lies about immigrants committing crime, harming low-skilled US workers and perpetrating terrorism.
Is this the real GOP view? As Brian Beutler points out, the legislative history here does betray sustained GOP treatment of the Dreamers in precisely these terms. Or, as David Bier puts it, House Republicans cannot "accept Dreamers as Americans" and view them only as "criminals on parole".
Indeed, to return to the point above, Trump's advisers are actively discouraging him from rhetorically treating them as sympathetic figures. All this is perhaps about maximising leverage later: If the Dreamers are just another species of criminal alien, then Democrats had better give up a lot - cuts to legal immigration and changes to family-based migration - to gain their protection.
But it remains unresolved whether Trump and Republicans are willing to legalise the Dreamers at all - whether they actually do or do not view them in sufficiently sympathetic terms. If they can't get to Yes - if no reasonable set of concessions is enough - it will be because treating the Dreamers as fundamentally different from other undocumented immigrants is a Rubicon they cannot cross.
Are the Dreamers nothing more than unwanted immigrants from "shithole countries"? We don't know how Trump and Republicans will resolve this question. But it can't be postponed forever.
