President Donald Trump is expected to take executive action to add a citizenship question onto the 2020 census during a ceremony at the White House on Thursday.

It's not quite clear what kind of action that will be. Trump has said he was considering an executive order, among other possibilities. Attorney General William Barr said this week that a legal path exists to get the question on the census, though he has not elaborated.

Any executive action, coming two weeks after Chief Justice John Roberts sided with the Supreme Court's liberal wing to effectively block the addition of the question, could have some political pay off, particularly for a president who has made battling with the courts a point of pride. But it is unlikely to result in the question being included on the survey, legal experts say.

"He is between legal rocks, spikes, a volcano, and earthquake faults. It's worse than a rock and a hard place," said Jessica Levinson, a law professor at Loyola Law School and director of the school's Public Service Institute. "This is a tough place to litigate your way out of."

The trouble comes from all sides.

On one side, the Supreme Court found that the administration "contrived" the stated rationale for asking the citizenship question when it said the question would assist in enforcing the Voting Rights Act.

To get over that, Trump will have to come up with a new reason for asking the question that passes muster. But coming up with a new reason that does not seem contrived could be difficult after more than a year of defending the Voting Rights Act explanation.

"Any kind of after-the-fact rationalization is going to look just like that, like an after-the-fact rationalization," said John Libby, a partner at the law firm Manatt who was part of a team that successfully argued against the addition of the question in federal court in California. "I just don't see how they can logically do that."

Marisa Maleck, a former law clerk to Justice Clarence Thomas and a member of the Appellate, Constitutional, and Administrative Law practice at King & Spalding, said any executive action would circumvent the process that Roberts laid out in his Supreme Court opinion, which sent the case back to the Commerce Department, not the president.

And she added that, in typical cases, the government cannot come up with a new reason this late in the game.

"Usually, in pure administrative law matters, you can't come up with a post hoc reason. You have to show it was the original reason. But this is entirely unprecedented. Could he come up with a new reason? I mean, he's president," she said. "It raises the specter of a constitutional crisis."

"They repeatedly said that complying with the Voting Rights Act was their one and only purpose," said Deborah Archer, a law professor at New York University law school. "It is hard to make a 180 on that and it is unclear that a court would accept the new justification on its face."

But even if the administration succeeds in providing a new rationale, there is trouble on another front.

The administration will also have to explain why the strict printing deadline the Commerce Department set for the census no longer applies. Administration attorneys emphasized that the administration faced a July 1 deadline to finalize the census in their plea to get the Supreme Court to hear the case before it was reviewed by an appeals court, an unusual step.

In his ruling, Roberts noted that the top court agreed to hear the case after the government argued that "the census questionnaire needed to be finalized for printing by the end of June 2019." According to the contractor printing the forms, R.R. Donnelley & Sons, the process will involve 600 million documents mailed to more than 130 million households.

"It's a pretty staggering process. That deadline was not a fake deadline," Maleck said.

To make matters worse for the administration, the Supreme Court is on its summer recess, in which justices typically travel, take vacations and teach law classes. If the administration was turned back by a lower court, the top court could hold an emergency session, but it does not generally do so.

The final hurdle for the administration is that the Constitution does not provide the president authority over the census, which could doom executive action. Instead, the Constitution provides for Congress to conduct the census.

"Congress delegated that authority to the Commerce Department. But in terms of the line of power, this is in Congress's bucket," Levinson said. "An executive order would be the executive branch trying to reach into that bucket. To me that breaks down our system of checks and balances, the fundamental bedrock of our system."

Regardless of the president's next step, it is already virtually guaranteed that it will face legal challenges. On Thursday, after Trump announced a conference on the citizenship question later in the day, the ACLU vowed to fight any executive action.

"The Supreme Court has spoken. The Trump administration's effort to add a citizenship question to the 2020 census is unlawful. If President Trump takes executive action, we will take legal action," Dale Ho, the ACLU attorney who argued the matter before the Supreme Court, said in a statement.

It is possible that the president uses Thursday's conference to sidestep the census issue entirely. Multiple outlets reported Thursday afternoon, citing unnamed sources, that Trump may drop his bid to put the question on the census and instead seek to obtain citizenship information through other means.