Trump erupted in a rage at Nielsen and other cabinet members over the alleged failure to make "progress towards sealing the border," the New York Times reported, in an episode later confirmed by multiple other media outlets. Nielsen was so angry at Trump's attack on her that she drafted a resignation letter, the Times reported, but didn't submit it. According to the Times, Trump also raged about the "continued failure of his administration to find a way to build a wall along the southern border". Loading The Washington Post said Trump's "blowup lasted more than 30 minutes". His face "reddened" as he railed that Nielsen must "close down" the border and shouted: "We need to shut it down. We're closed."

Now, over to Paul Ryan. Vulnerable Republicans in the House are pushing a discharge petition that would force a vote on immigration bills, including two measures that would legalise the dreamers, one of them packaged with fortifications to border security. (Dreamers are the children who were bought illegally into the US by their parents; and whose status was protected under a law introduced by Barack Obama). Seventeen Republicans have signed the petition, meaning that if organisers can get eight more, it would pass - forcing a full House vote on whether the dreamers will be protected or remain in limbo. Ryan is trying to stop this from happening. He justifies this by claiming that there's no sense in voting on measures protecting the dreamers that Trump would veto. As Ryan put it: "We actually would like to solve this problem, and that is why I think it's important for us to come up with a solution that the President can support." But this is utter nonsense, because there isn't any deal that Trump is willing to support that can pass Congress. Ryan knows his suggestion otherwise is a big lie, because we already tried this. Congressman Paul Ryan knows there isn't any deal that Trump is willing to support to protect the so-called dreamers. Credit:AP

Earlier this year, Democrats repeatedly offered Trump deals with wall money in exchange for protecting the dreamers, and he rejected them all, because Trump also wanted deep cuts to legal immigration. After that, multiple immigration packages failed to pass the Senate. The one based on Trump's framework - citizenship for 1.8 million dreamers traded for $US25 billion ($33 billion) in wall money and deep cuts to legal immigration - got the fewest votes, at 39, with 14 Republicans defecting. Loading The bottom line is that Trump will not accept anything that protects the dreamers unless it also contains deep cuts to legal immigration. But nothing like that can pass Congress, because it faces bipartisan opposition. Trump's tirade at Nielsen is a reminder that he is the real obstacle to any deal protecting the dreamers.

It reminds us of Trump's bottomless irrationality on this issue: Border crossings have been at historic lows, but Fox News keeps telling him the border is overrun by invading dark hordes, which makes it true. He is still demanding his wall, but even when that has been offered in exchange for protecting the dreamers, he has rejected it. Yet he raged at Nielsen over the lack of movement on the wall, showing himself unable to comprehend that his own deeply unreasonable demands - which have been rejected by many Republicans - are the real obstacle to getting it built. Indeed, it has become undeniable that Trump's overriding goal on immigration is to reduce the number of immigrants in the US to the greatest degree possible. Loading As Eric Levitz notes on nymag.com, Trump moved to end Temporary Protected Status for various groups with no credible rationale for doing so and even though US diplomats have warned that it is dangerously bad policy.

And as Trump's "shithole countries" comment confirmed, his main driving impulse on immigration is white nationalism - rolling back the current racial and ethnic mix of the country at all costs - and that this is shaping policy. The real reason Ryan is blocking a vote on the dreamers Ryan is trying to prevent a vote to protect the dreamers precisely because such a measure could pass the House. That would expose him to the right's rage and would probably end up forcing Trump to make the terrible choice of accepting or vetoing it. A deal protecting the dreamers in exchange for border security would probably pass the House by a comfortable margin, and it might pass the Senate - after all, passage in the House would bring tremendous pressure on moderate Republican senators - especially if the White House didn't actively lobby against it. But Trump will not accept any deal to protect the dreamers, even though it could very likely pass both chambers, unless it also contains deep cuts to legal immigration.

So if the House passed it, the White House would lobby the Senate against it, and if that failed, Trump would then have to veto it. Either of those would look horrible, because after House passage, suddenly protections for the dreamers would appear in reach. This is the spectacle that Ryan is trying to avert - all to protect Trump from having his true priorities revealed in all their ugly glory. Washington Post