There are two likely explanations for the Justice Department replacing its legal team in the census citizenship question case. Neither of them is good, and one could signal something much worse lying ahead.

The Justice Department announced the moves Sunday, as The Post’s Matt Zapotosky reported, and there is at least some indication that it was because the lawyers had qualms about the direction in which this was heading:

A person familiar with the matter, who spoke on the condition of anonymity to discuss internal deliberations, said that at least some of the career attorneys harbored concerns about the administration’s handling of the case — although the nature of those concerns and how widespread they were could not immediately be learned.

Another not-mutually-exclusive possibility is that the lawyers had seen their credibility shot by changing their minds about how to proceed. The old legal team told a judge last week that they were done, and Commerce Secretary Wilbur Ross waved the white flag publicly too, before President Trump reversed the administration’s course in a tweet.

The lawyers admitted in court proceedings and filings that they didn’t initially understand what Trump’s tweet meant and that they weren’t sure what rationale would be used to defend the census citizenship question moving forward. The Supreme Court two weeks ago rejected the question’s inclusion and said the justification offered was “contrived.” It left open the possibility, though, that the administration could offer a new rationale that would pass muster.

In a conference call with a judge, one career attorney practically begged for understanding from the judge and admitted he did “not have a deeper understanding of what [Trump’s tweet] means at this juncture other than what the president has tweeted.” In another court filing on Friday, the Justice Department said it was still looking for a “new rationale for reinstating a citizenship question.” The continued search for a rationale — and admitting that one has yet to be found — does not suggest that the new one won’t be as “contrived” as the last one.

We don’t know what has happened behind closed doors here. But the fact that both the Justice Department lawyers and Ross signaled defeat suggests this was a decision that had been well-considered and made before Trump threw the whole thing into chaos with his tweet. And if that decision was made, you have to believe there weren’t a whole lot of good options available for proceeding.

And that’s where the news Sunday could really matter. Option No. 2 — that the existing legal team torched its credibility, regardless of whose fault that was — would be embarrassing. (The same legal team argued that June 30 was a hard deadline for deciding the case, which it now tacitly admits wasn’t the case.) But if this is more Option No. 1 — that the existing lawyers opted not to be involved in the continuing case — that signals a potentially large mess to come.

It’s not unheard-of for Justice Department lawyers to withdraw from a case over personal objections, but this case in particular raises all kinds of legal and constitutional questions.

Trump has signaled that he may pursue an executive order, for instance, which would have the effect of going around the Supreme Court’s ruling. Some have suggested this would amount to a constitutional crisis, in which the administration does something that has explicitly been rejected by the nation’s highest court. The Supreme Court didn’t explicitly reject the possibility that the question would be legal, it bears noting, but rather said the provided rationale wasn’t genuine. A new executive order would also be subject to legal review.

And secondly, the administration’s struggles to settle upon a new rationale in the ongoing legal case suggest whatever it ultimately produces may be pretty brazen. Some have even floated the idea that the administration would just admit it wants to give states the ability to draw districts using the citizenship data — something GOP map-drawers have long craved and Trump alluded to Friday, despite the administration previously saying that wasn’t part of its rationale — or even just flat-out admit that this was intended for partisan gain.

The latter would be extremely bold, but Chief Justice John G. Roberts Jr.’s opinion blocking the citizenship question suggested the administration should have broad latitude to add such questions to the census. And the same day this decision landed, the court ruled that it wouldn’t reject redistricting plans because of partisan gerrymandering.

Whatever the new rationale is, squaring it with what the administration said before will probably be very difficult. That by itself might be a good reason to ditch the existing legal team, given that it made the arguments initially. But if this is about internal discord over how the administration is proceeding on this question, we may not have seen the worst of this situation yet.