While Washington obsesses over a new book on White House intrigue, the Trump administration is reaching a critical point on the issue of immigration, one of the president's top priorities and the subject of his most often-repeated campaign promises.

There are multiple moving parts: The Deferred Action for Childhood Arrivals program, a border wall, chain migration, the visa lottery, and — hanging over it all — funding the government. But everything hinges on DACA, unilaterally imposed by Barack Obama to temporarily legalize nearly 800,000 people who were brought to the U.S. illegally when they were young.

When President Trump rescinded DACA last Sept. 5, he delayed implementation for six months to give Congress time to come up with some sort of solution for the so-called Dreamers. That means lawmakers need to act by March 5 or face a decidedly uncertain future.

Nearly everyone on Capitol Hill wants a fix that results in legalization for the Dreamers. Democrats want to legalize right away, straight up, no strings attached. But Trump and most Republicans want a deal: immigration reforms — the wall, chain migration, visa lottery — in exchange for legalization.

That's where funding the government comes in. A temporary funding resolution passed last month expires on Jan. 19. Congress can pass a "clean" bill to avoid a partial shutdown, or it can have a fight if one party tries to attach unrelated policy preferences to the must-pass spending bill.

That is the traditional Republican role, which has led Republicans to believe that they always lose shutdown fights. But it is probably more accurate to say that Republicans don't always lose shutdown fights — it is the party that tries to attach unrelated policy preferences to must-pass spending bills that loses shutdown fights. In the past, that has been Republicans. This time, it might be Democrats.

The Senate's No. 2 Democrat, Dick Durbin, appears to be itching to set off a shutdown crisis over DACA. "President Trump has said he may need a good government shutdown to get his wall," Durbin said recently. "With this demand [for wall funding], he seems to be heading in that direction."

But Trump, who in the past has threatened a government shutdown over the wall, is now proposing trading his policy preferences — the wall, etc. — in exchange for DACA legalization. "The wall is going to happen, or we're not going to have DACA," he said recently. He hasn't demanded they be passed in order to keep the government running. Durbin is suggesting Democrats demand DACA passage to keep the government in business.

It's a losing strategy. Democrats could have pursued it when government funding came up in December. But when push came to shove, they didn't. Now, will they try for real?

"If the government were to shut down because of DACA, it would elevate the question of amnesty for these illegal immigrants far beyond the status it has now," says one GOP lawmaker. That seems less likely to capture the voters' attention than a question of shutting down the government.

It's one thing to block a DACA fix because of a policy demand — in this case, the wall. But it's a much different thing to force a partial government shutdown because of a policy demand. Durbin and Democrats are likely to find that out, if they don't already know.

Assuming the government is funded, with either a long-term or kick-the-can short-term measure, the DACA negotiations will start in earnest ahead of that March 5 deadline.

Can Trump get what he wants, or part of what he wants? At the moment, Democrats seem determined to throw their bodies in front of any plan to build a wall. The president has asked Congress to put aside $18 billion over the next ten years for the job. That seems doomed.

But what about some other idea? What about passing a down payment — the House has already approved $1.6 billion — as part of another plan?

"One possibility would be a relatively modest down payment that Democrats could swallow," said the GOP lawmaker, "and then authorization for a user-fee model for future years. So a fee for visas or border crossings could be turned into a dedicated revenue stream for wall construction." (That would, by the way, mean that, yes, Mexico pays for the wall, or at least a significant part of it.)

The president also wants a measure to stop chain migration, and perhaps a provision to end the visa lottery, too. It seems highly unlikely he would get it all. But he might get something.

Trump will be offering permanent legalization for those nearly 800,000 Dreamers, or perhaps for an even larger group referred to as DACA-eligible. It depends on whether Democrats believe that giving Trump something in return is the only way to achieve that legalization.

It is a decisive moment in the Trump presidency, and in the debate over immigration. Right now, it's fair to say nearly no one in the Washington press corps is paying much attention — they would much rather discuss Steve Bannon, or the 25th Amendment, or whether the president watches too much TV. But the coming weeks will be crucial for the agenda that won Donald Trump the White House.