President Donald Trump outlined the basic structure of a DACA deal on Sunday.

The so-called “Dreamers” — illegal aliens brought to the U.S. as minors — would be able to stay legally in the country, but only if a border wall is built.

(DACA refers to the Deferred Action for Childhood Arrivals policy, an Obama-era program that covers some 800,000 “Dreamers” and is arguably unconstitutional. Trump canceled it in September, effective March 2018.)

Trump’s deal might be acceptable to conservatives, as long as the wall comes first and there are other safeguards, like mandatory e-verify and an end to chain migration. But Democrats seem convinced they can hold out for more.

First of all, Democrats believe that they have all the political momentum. They think that they are going to ride a wave to victory in the midterm elections in November. Moreover, talk of removing the president from office, either by impeachment or the use of the 25th Amendment, has many Democrats believing time is on their side.

Second, while some DACA beneficiaries will begin losing their protective status in March, few Democrats are really worried that the Trump administration will begin deporting them. They believe the president does not have the nerve to do it, any more than Republicans have the nerve to allow a government shutdown. And Democrats are prepared to let the problem fester, as they have for years, the better to use it to motivate Latino voters in November.

But the third and most important reason that Democrats are unlikely to agree to a reasonable DACA deal is that they are incapable of compromising with President Trump on anything. The proof is in the recent tax reform law. Democrats suffered a major setback when Republicans capped the state and local tax (SALT) deduction. That will hit wealthy taxpayers in liberal blue states, and will encourage many to leave for low-tax red states.

Losing SALT could even spark a conservative revival in some blue states, as taxpayers fight back.

Democrats probably could have preserved SALT if they had worked with Republicans on, say, reducing the corporate tax rate, which most agreed needed to be done. But because they refused to be seen helping Trump, they lost — and lost big.

If Democrats will not even reach agreements in Trump when it is in their direct self-interest to do so, how will they negotiate with Trump on a DACA deal?

The answer is that they will probably walk away from the table, leaving the Republicans to deal with the fallout of that failure. They will then count on Trump deferring enforcement until November at the earliest, when they hope to regain control of Congress and return to negotiations on better terms.

There is only one way to force Democrats to accept even a moderate compromise on DACA, and that is for the Trump administration to stick to its March 6 deadline. On that date, DACA work permits will expire, and DACA beneficiaries could face deportation. Once Democrats understand that Republicans are serious — and Trump’s decision to end protections for El Salvadorans is a sign that they are — they will feel greater pressure to negotiate.

In addition, Republicans should call Democrats’ bluff on a government shutdown. Democrats seem to think that they can win any shutdown showdown, based on more than two decades of experience. But those showdowns happened when Republicans were in the opposition and Democrats controlled the White House.

DACA is not popular enough to sustain Democrats through a shutdown. If Trump stands his ground, Republicans can win.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named to Forward’s 50 “most influential” Jews in 2017. He is the co-author of How Trump Won: The Inside Story of a Revolution, is available from Regnery. Follow him on Twitter at @joelpollak.