If the goal is to build a border wall, then President Trump has made the wrong decision at every turn. In early 2018, Trump had the opportunity to secure $25 billion in funding for his border wall in exchange for legal status for Deferred Action for Childhood Arrivals recipients. Instead of taking the deal, he blew up the negotiations with his “shithole countries” remark and by demanding changes to legal immigration policy.

Then in June, the Senate Appropriations Committee approved $1.6 billion for 65 miles of fencing by an overwhelming bipartisan 26-to-5 margin. This could easily have passed the House and Senate. Instead, Trump later shut down the government over wall funding and demanded $5.7 billion. Result? After a disastrous 35-day shutdown, he got less – $1.38 billion – than he would have if he had just gone along with the bipartisan deal six months earlier.

The smart move for Trump would have been to pocket that $1.38 billion and bolster it with another $3.1 billion he could arguably use without a declaration of a national emergency – by reprogramming $600 million from the Treasury Department’s drug forfeiture fund and $2.5 billion from the Defense Department’s drug interdiction program. That would have given him $4.48 billion in wall funding – nearly the full amount he was demanding from Congress. Then, in December, he could demand more money with leverage over Democrats when an automatic sequester kicks in, forcing $55 billion in across-the-board cuts to domestic discretionary spending unless Trump agrees to raise spending caps.

Instead, Trump has made the wrong move once again – declaring a national emergency, despite warnings from Senate Majority Leader Mitch McConnell, R-Ky., and other Republicans that it could provoke a backlash from within his own party.

His order will face an immediate court challenge, which means he won’t be able to spend the emergency funds any time soon, if at all. And if he prevails in court, it will be a disaster for the cause of limited government. If Trump can declare a national emergency to build a border wall Congress refused to fund, then the power of the president to override Congress’ power of the purse will be virtually unlimited. As Rep. Cathy McMorris Rodgers, R-Wash., pointed out, a future liberal president could declare climate change a national emergency and “force the Green New Deal on the American people.”

Just as the Democrats’ decision to end the filibuster on lifetime judicial appointments below the Supreme Court set precedent for a Republican rules change to put two justices on the Supreme Court, Republicans will rue the day if they go along with Trump’s executive power grab. Over a dozen Senate Republicans, including Susan Collins, have spoken out against his emergency declaration. If their votes comport with their words, that is more than enough to pass a resolution of disapproval.

In fact, every Republican in Congress should vote for such a resolution. Stopping executive overreach and restoring Congress’ Article I powers was a key plank in Republicans’ 2016 Better Way agenda. “Our President has been acting more like a monarch than an elected official,” House Republicans declared. “That stops now.”

Trump would no doubt veto a resolution. But the fact that a bipartisan majority of both houses voted to overturn Trump’s declaration would bolster the legal case against his action. As Justice Robert Jackson wrote in a concurring opinion for Youngstown Sheet & Tube Co. v. Sawyer, presidential powers “are not fixed but fluctuate, depending upon their disjunction or conjunction with those of Congress.”

When a president acts with congressional support, his power is “at its maximum.” When Congress has not spoken, “there is a zone of twilight.” But “when the President takes measures incompatible with the expressed or implied will of Congress, his power is at its lowest ebb,” Jackson declared. A disapproval resolution would make clear that not only is Trump ignoring the will of Congress, but also Congress has further expressly disapproved of his actions.

Trump’s defenders will argue that Republicans should not deliver such a rebuke to their president. In fact, the opposite is true: It is Trump who should not be forcing Republicans to choose between fidelity to their president and fidelity to the Constitution. And if forced to choose, they must choose the Constitution.

Washington Post columnist Marc A. Thiessen is a fellow at the American Enterprise Institute and former chief speechwriter for President George W. Bush.

Twitter: marcthiessen