Observers believed President Trump might make an announcement declaring a national emergency declaration on Tuesday night during his nationally televised speech on the border and a border wall.

He didn’t — at least not yet. But that’s not because he didn’t want to.

Opposition to declaring a national emergency over the border came from a surprising source: prominent conservatives who support Trump. They feared the expansive move in presidential powers that such a declaration would represent was simply too much to bear — after all, Democrats are bound to recapture the White House sooner or later, and the precedent Trump set could free up future presidents to declare their own expansive crises.

As former Judge Andrew Napolitano pointed out on Fox News, President Barack Obama could have declared a state of emergency to address health care reform, “but obviously he didn’t, because he couldn’t.”

Trump has been holding the threat of declaring a national emergency to get a border wall built between the United States and Mexico over Democrats in the partial government shutdown fight, which is entering its third week.

“We’re looking at a national emergency because we have a national emergency. Just read the papers,” Trump told reporters Sunday. But though many experts agreed Trump did have the authority to declare one — essentially leaving Congress and the courts to rein him in — the conservative talking heads may have been the ones to stop him.

This, below, is a live political concern for the White House, which is counting on the suppport of folks who slammed Obama for violating constitutional norms. https://t.co/VN0gUVrIHE — Eliana Johnson (@elianayjohnson) January 8, 2019

Yes, a state of emergency was possible

While the “crisis” at the border is largely manufactured by Trump, the powers he could use to declare a state of emergency to get a border wall built really do exist. As Elizabeth Goitein, a co-director of the Liberty and National Security Program at the Brennan Center for Justice, told my colleague Emily Stewart, “He has broad leeway to declare an emergency, frankly, whether one exists or not.” (Not to mention, he wouldn’t be the first president to do so.)

The authority rests likely in a section of US code, 10 US Code § 2808, which offers the president authority to direct the military to take on construction projects following a state of emergency declaration, and 10 US Code § 284, which authorizes counter-drug efforts.

If Trump declared an emergency “that requires use of the armed forces,” the law says the secretary of defense “may undertake military construction projects, and may authorize the Secretaries of the military departments to undertake military construction projects, not otherwise authorized by law that are necessary to support such use of the armed forces.”

However, neither law is quite broad enough to permit Trump to use to do what he wants here, and his actions would likely face a major challenge in court, even if he had support from a few in Congress. But as Stewart explained, Congress can overturn a national emergency, but it may not be easy:

The National Emergencies Act contains a mechanism for Congress to overrule the president by passing a joint resolution out of the House and Senate. With Democrats in control of the House, it would presumably pass there easily, and Ackerman, the Yale professor, says he believes it could pass the Senate, too. “Mitch McConnell does not have the power to bottle this up,” he said. “So that means that there would be a moment of truth for the Republican Party.” But thanks to a 35-year-old court case, Congress might not be able to override the president that easily. In the 1983 case Immigration and Naturalization Service v. Chadha, the Supreme Court decided that a one-house legislative veto violated the Constitution. After that, the National Emergencies Act was amended to require the joint resolution to override the president’s declaration — like a typical law, it requires a simple majority in the House and Senate and the president’s signature.

Trump would be unlikely to sign a law that overturned his own declaration.

Ultimately, though, the biggest question facing conservatives and the right wasn’t “can Trump declare a state of emergency to get a wall built?” but “should he?”

The politics at play in a state of emergency declaration

Among conservatives, including those who are strongly in support of a border wall, the debate over a potential national emergency declaration was less about whether a wall in the style Trump promised time and again during the campaign is necessary than about the powers a president has, and should have.

To be clear, there was significant support from some of the most prominent voices on the right — like Fox News’s Sean Hannity — for both the border wall and a state of emergency declaration to fund it, with Hannity arguing on his television show that the situation at the border “is a national emergency.” (For the record, it isn’t.) And other conservative pundits voiced support for a national emergency declaration, only worrying that the courts might get in the way.

Presidential adviser and Fox host Sean Hannity: "This is a national emergency, it's time to build the wall." pic.twitter.com/co4huBNU3R — Matthew Gertz (@MattGertz) January 8, 2019

But even on Fox News, there has been dissent — not over the wall, but over whether declaring a state of emergency is the right way to get it.

On Monday, Napolitano argued on Fox Business that US law requires Trump to get congressional authorization to fund border construction, saying, “the Supreme Court has made it very clear, even in times of emergency, the president of the United States of America cannot spend money unless it has been authorized by the Congress.”

And on Tuesday, Napolitano said very much the same on Fox & Friends, arguing also that even a state of emergency wouldn’t allow the Trump administration to take or occupy the land needed to build the wall, which Trump had referenced doing via the “military version of eminent domain.” And he added that if President Obama had had the power to go around Congress and declare states of emergency to deal with health care instead, he would have done so — concluding, “but obviously [Obama] didn’t, because he couldn’t.”

Meanwhile, Andrew Napolitano says trying to fund the wall through a national emergency declaration would be unconstitutional. pic.twitter.com/x7BqUmMOiv — Matthew Gertz (@MattGertz) January 8, 2019

I reached out to David Bier, a policy analyst at the Cato Institute, who agreed with Napolitano, telling me, “The executive branch cannot spend money without congressional authorization, and if the president tries to build the wall, he will have to cite a statute that gives him the authority to do that. Given that no such explicit authority exists, challenges will come to prevent the money from being spent. The administration will cite vague statutes that give it powers to spend money on ‘national defense.’”

The real debate is over the power of the presidency

But Bier pointed out something else that has troubled many on the right: The precedent such a move would make would dramatically increase the power of the executive branch. “It would force Congress into the position of ruling [over] giving any discretion to the president at all to spend on national defense matters or lose all control over defense spending,” he told me. “It would allow presidents to spend defense money on their domestic priorities in the name of ‘national security.’”

And he’s not alone in worrying about the example giving Trump a state of emergency would set for future presidents. As National Review writer John Fund pointed out over the weekend, Trump’s current stance on executive overreach stands in direct opposition to the criticism he (and many conservatives) leveled at Obama. And if Trump were able to use a national state of emergency to get something he wants (and most Americans don’t), what would stop a future president from doing the same — on health care, or criminal justice reform, or the debt ceiling, or virtually any other subject that could be turned into a “national emergency”?

If the President declares a national emergency and starts using eminent domain and reprogrammed dollars to build a wall, it is only a matter of time before a progressive President declares climate change a national emergency and uses eminent domain to shutter coal plants, etc. — Erick Erickson (@EWErickson) January 8, 2019

National Review columnist Jonah Goldberg argued in a piece published on Monday, “Do we really want to establish the precedent that the president can simply declare ‘It’s an emergency’ like some magical incantation and then completely bypass property rights and the will of Congress just so he can fulfill a campaign promise that, if Sam Nunberg is to be believed, began as a consultant’s gimmick to get the candidate Trump to talk about immigration and what a great builder he is?”

Goldberg added in a piece published Tuesday that “declaring a national state of emergency to use military powers to solve a problem that was no less ‘grave’ a year ago is grotesque.”

Conservative commentator Ben Shapiro told me via email, “The law was designed to allow the president to act when no other options were available in a time of immediate crisis — not to handle a decades-long problem. Allowing the executive branch to declare a national emergency along these lines opens the door to yet more executive usurpation.”

It’s clear then that if Trump declared a state of emergency in his address to the nation tonight, he wouldn’t just have needed to make the case to the courts. He’d also have to make it to conservatives and Republicans who support his border wall but not the extension of presidential powers. And that was apparently one step too far.