President Donald Trump on Friday decided that the cooperation of Congress, an equal branch of government, is simply irrelevant in what has been his mostly fruitless pursuit of a border wall. Unwilling to accept defeat, he declared a national emergency to do what no other U.S. president has done: Use those emergency powers to seize billions of dollars of federal funds he was unable to obtain legislatively.

Trump has failed to persuade either the public or Congress of the need for his wall. He failed during the two years Republicans controlled the House and Senate. He shut down government and still failed to get more than a sliver of the funding he sought. The democratic process that has guided this country since its inception dictates that, at some point, the president accept a compromise and move on.

The case for a national emergency is particularly weak precisely because Trump has waited so long to employ it. An emergency, by definition, is immediate. Yet he did not consider it an emergency through two years of GOP congressional control. Is it an emergency now because of record border crossings? Hardly. Illegal entries remain at a decade low. Is it an emergency, perhaps, because hordes of terrorists are gaining entry through the Southern border? No such data have been presented. Drug smuggling? That tends to occur at legal ports of entry. Better detection, more agents and widespread treatment for addicts would curtail smuggling far more than a wall.

The sad reality is that Trump’s border crisis is a political device of his creation that now threatens to undermine the separation of powers that is the foundation of a system built on checks and balances.

Sen. Susan Collins, R-Maine, said that Trump’s declaration would “undermine the role of Congress and the appropriations process … It also sets a bad precedent for future presidents — both Democratic and Republican — who might see use this same maneuver to circumvent Congress to advance their policy goals.”

The Constitution gives Congress the power of the purse. Contrary to Trump’s apparent beliefs, he and Congress are on equal footing. He proposes, but Congress disposes. Trump rejected the democratic process that gave him only $1.375 billion of the $5.7 billion he sought for a wall. That amount was the result of difficult negotiations forged by a Republican-led Senate and Democratic majority House, part of an effort to avert a second government shutdown. When Trump signed the bill, he signaled acceptance of its terms. That should have been the end of it. He was, of course, free to continue to make his case in the next round of budget talks.

The National Emergencies Act in recent times has been used primarily in dealing with hostile foreign nations, to freeze assets, prohibit transactions or impose economic sanctions. In making such expansive use of the act, Trump potentially takes this country on a different path. Congress would become a shell, appropriating funds and crossing its fingers that the president would not simply overrule its choices.

And in his money grab, Trump appears to no longer be content with the $5.7 billion he originally sought. Now he wants $8 billion, raiding funds from previous congressional appropriations and existing programs.

Trump, in his news conference, seemed to acknowledge the shakiness of his legal argument. But he also appears to believe that the Supreme Court, with its conservative majority and two Trump appointees, will side with him if he loses lower court rulings. “And then we’ll end up in the Supreme Court,” he said, “and then hopefully we’ll get a fair shake.” That, of course, would come only after months of court battles that could further polarize this nation just as the 2020 election cycle crests.

Congress still has a chance to spare the nation such a drama. The emergency act Trump is relying on also says that Congress can vote to check his power grab. A veto-proof vote would end it, while reaffirming to the president and the public that the separation of powers still matters in this country.