“Dreamers” during the Keep Our Dream Alive binational meeting. (Jose Luis Gonzalez/Reuters)

If Congress cannot agree on a budget plan by Jan. 19, the government will shut down. This isn’t the outcome anyone wants. But Democrats ought to start steeling themselves now: If the Republican majority’s budget plan leaves the “dreamers” in limbo, fails to supply desperately needed aid to Puerto Rico and coastal states battered by natural disaster, or allows the Children’s Health Insurance Program (CHIP) to wither away, Democrats need to be ready to shut the whole thing down.

It is necessary to recognize the damage a shutdown could cause in the course of recommending, as I am, that the Democrats prepare to let it happen. If the outcome were sure to be harmless, the possible costs would be small. But the moral stakes of this budget negotiation are extraordinarily high. Taking a stand for dreamers, children and disaster-stricken citizens will come with a price.

Trump has said a shutdown could be politically useful for him, and Democrats seem nervous. It’s hard to predict, at this point, which party (if either) a shutdown would benefit: Republicans could wind up with the blame, but they could also gain from underscoring the notion that government is broken. As Jared Bernstein, a senior fellow at the Center on Budget and Policy Priorities and a Post contributor, warned me on Wednesday: “These government shutdowns feed into a narrative that is not politically neutral.”

Opinion writers Charles Lane, Molly Roberts, Jennifer Rubin and Dana Milbank talk about the chances of a DACA deal in this clip from the weekly news roundup "It's Only Thursday." (The Washington Post)

There are practical concerns, too. “The biggest impact tends to be on people who work for the government [and] are nonessential employees,” Bernstein said. During past shutdowns, nonessential employees have been paid after the fact, but there is no guarantee Congress would elect to do the same this time. Bernstein added that a shutdown would be “a ding to the economy” and “massive inconvenience,” putting all kinds of activities — from sorting out Social Security questions to visiting national parks to getting passports renewed — on hold. A shutdown wouldn’t grind daily life to a halt. But it would affect millions, with serious ramifications for many.

But there are potential strategic upsides for Democrats. For one, triggering a shutdown could demonstrate that Democrats take the interests and desires of the American people seriously. “The public wants CHIP, Puerto Rico and Texas to get relief, and wants to protect dreamers,” said Ben Wikler, Washington director of MoveOn.org. “Keeping all these priorities on hold in a perpetual game of kick-the-can doesn’t actually line up with what most Americans want.”

In an October Kaiser Family Foundation poll, 62 percent of respondents said Puerto Rico has not received the help it needs in the wake of Hurricane Maria; a November Kaiser survey likewise found that 62 percent of Americans consider funding CHIP a top priority — far above tax reform or strengthening immigration controls. In that same poll, only 16 percent of respondents said dreamers shouldn’t be allowed to remain in the country. Likewise, a Post-ABC News poll found that 86 percent of Americans want dreamers to be allowed to stay.

But it isn’t just the premise of democracy or the possibility of 2018 advantage that demands relentless commitment to these three causes. It’s ordinary morality.

The beneficiaries of CHIP, disaster aid and Deferred Action for Childhood Arrivals are innocent insofar as none of them brought onto themselves the statuses that have made them vulnerable. It is important to understand them as innocents at the mercy of a merciless faction; otherwise the harms they face might appear more morally complicated than they are. As the Roman Catholic Archbishop José Gomez recently wrote: “It would be cruel to punish [dreamers] for the wrongs of their parents, deporting them to countries of origin that they have never seen, where they may not even know the language.” It would likewise be cruel to allow children with diabetes to die for lack of insulin or to plunge poor families deep into debt because they happened to have a child with a disability. The same can be said for those who had the misfortune of living in areas struck by storms, the ne plus ultra of situations one didn’t cause and cannot prevent.

A shutdown would cause real problems for real people. It is, in the words of Wikler, “something to be avoided if possible, but not at the expense of fundamental priorities.” What is remarkable about the priorities at hand, however, is that they have no business being articles of compromise. These aren’t ordinary policy squabbles; they constitute a choice between America as a humane nation with democratic principles and America as a negligent sovereign with a dim future. The protection of innocents shouldn’t be up for debate. But it is. And Democrats can’t back down.