For 20 years, the shining moment for the Republican Party was Ronald Reagan, standing in Berlin, commanding Soviet leader Mikhail Gorbachev: "Mr. Gorbachev, tear down this wall." Needless to say, today's Republican Party is no longer Reagan's.

Today's GOP belongs to President Trump, though America does not. Trump is a historically unpopular president, his party lost the House in spectacular fashion in the last election, and he just declared a very unpopular "national emergency" to sidestep Congress and use the military to build his slightly less unpopular border wall.

It's likely Trump will be able to build some of his wall — with America footing the bill. The next president should demolish whatever Trump manages to erect. Not out of spite, but out of necessity.

Trump took executive action on his border wall because that was really the only option he had left. He was unable to get Congress to open America's wallet for more than 55 lousy miles of border fencing, even after two years during which his party controlled Congress, even after shutting down the government for 35 days. The 1976 law he used, the National Emergencies Act, has been used quite a few times by numerous presidents, but it has never been used quite like this, to pursue a controversial policy goal after Congress repeatedly declined to fund it.

Seizing the power of the purse specifically given to Congress by the U.S. Constitution is legally questionable, taking money from military construction and drug interdiction accounts is politically problematic, and declaring what's been happening along the U.S.-Mexico border for decades an "emergency" borders on lexicological abuse. It's also entirely counter to the stated opinion of the U.S. intelligence agencies.

But as Trump has shown over and over again, constraints are for suckers (and Democrats). Can Democrats stop him? It doesn't look like it. Will the courts? Maybe at first, but the Supreme Court is a crap shoot. And as Conn Carroll, communications director for Sen. Mike Lee (R-Utah), points out, only $3.6 billion of the more than $6 billion Trump plans to spend on the wall relies on his emergency declaration, and he plans to spend that money last. So even if the courts rule Trump's emergency declaration unconstitutional, he's likely to get at least some of his wall built anyway.

Trump, more than anyone, should understand the risks of enacting policy through executive fiat. Since taking office, he has been on an almost monomaniacal quest to erase the legacy of his predecessor, former President Barack Obama. Things he could do through executive action — gut regulations, withdraw from international agreements Obama negotiated and championed, and undermine laws he couldn't overturn — he's done. The American system makes enacting policies a challenging exercise in consensus-building, and that's on purpose. It was designed that way consciously by the country's founders. Executive action short-circuits that process.

Conservatives, like Lee and The Week's Ed Morrissey, argue that Congress shares a good deal of blame for the current national emergency situation because it has steadily ceded power to the executive branch for decades, and that is true. It would seem in the best interest of constitutionally conservative Republicans to take a stand here. But if they don't, there is one final remedy: elections. And the next president, whether elected in 2020 or 2024, should destroy any wall Trump constructs in this manner — and announce the intention to do so publicly, so Trump will know what's coming, and so will the courts and the soldiers or contractors who build it.

You could view this proposal as a call to waste even more taxpayer dollars to own Trump, to castrate his vanity project, leaving a pile of rubble to embarrass him and show him that, as is written in Ecclesiastes: "Vanity of vanities! All is vanity." Or in the transition from the band Kansas: In the end, "all we are is dust in the wind."

But this is about more than that. Much more. It's about protecting America's grand experiment in government, which the founders placed upon three legs, expecting each one to jealously guard its given powers. And it's also about raging against the dying light of Reagan's shining city upon a hill. Here's how he described that vision in his presidential farewell address:

I've spoken of the shining city all my political life, but I don't know if I ever quite communicated what I saw when I said it. But in my mind, it was a tall proud city built on rocks stronger than oceans, wind swept, God blessed, and teeming with people of all kinds living in harmony and peace — a city with free ports that hummed with commerce and creativity, and if there had to be city walls, the walls had doors, and the doors were open to anyone with the will and the heart to get here. [Ronald Reagan, 1989 farewell address]

In The New York Times, New York University history professor Greg Grandin describes Trump's wall as "a monument to disenchantment, to a brutal geopolitical realism: Racism was never transcended; there's not enough wealth to go around; not everyone in the global economy can have a seat at the table." Where America's boundless physical — then ideological — frontier "once symbolized perennial rebirth, Donald Trump's border wall — even if it remains mostly phantasmagorical, a perpetual negotiating chip between Congress and the White House — now looms like a tombstone," Grandin adds.

Trump's wall is a symbol of defeat and failure, his and ours. We can accept that, or we can act.