So it comes to this: Mitch McConnell refuses to permit the Senate to consider legislation passed by the House that would reopen the federal government in order to protect Donald Trump from either having to accept it and cave on the border wall or reject it and draw further blame for the shutdown. It’s been this way for weeks and there is no end in sight. We’re in this holding pattern, leaving hundreds of thousands of federal workers and contractors without income and millions of others feeling real-world pain, because the Republican Party has been unwilling to confront the damning lesson of the 2018 election.

The lesson is if you’re a Republican representing a district or state with more people than cattle, it won’t do you much good in a general election to be identified with Donald Trump. This is an unpalatable lesson because it is also true that breaking with Trump is a recipe for political oblivion in primary races. In other words, the Republican Party faces an existential crisis of its own making from which there is no exit, and the government itself is now being held hostage to that crisis.

For two years, Republicans have cowered at the thought of primary opponents fueled by base voters who make up Trump’s core support. They still do, because they feel their political survival depends on preventing what happened to former Rep. Mark Sanford, whose criticism of the Muslim ban drew presidential wrath, a primary challenger, and an early exit from Congress. In many red districts, this remains a more immediate fear than general election defeat. The party as a whole risks undermining its general election position by enabling the administration, and individual members risk general election challenges in constituencies once thought to be immune to Democratic candidates, but these concerns seem more abstract and distant at this point in the political cycle, even though they should be abundantly clear after Democrats overcame a supposedly impenetrable gerrymander and easily reclaimed the House in one of the largest wave elections in history last November.

The political realities ensnaring Republicans have a parallel in the trap facing Trump himself. Having shut down the government to get funding for a key priority that no one outside his base wants, he finds himself beholden to his supporters but without the political pull he needs to get his wall. With a majority of the country blaming him for a government shutdown that inches daily toward catastrophe, he is watching his approval sink steadily downward from already tenuous depths. But like his counterparts in congress, he has no way out. Saturday’s forgettable address from the White House, offering Democrats nothing of value in exchange for everything he wants, shows how little freedom he has to negotiate on immigration and how desperate he is to extract himself from this situation.

The source of the dilemma confounding Trump and his party is the unusual dynamic of Republican Island. Donald Trump and the Republican Party are handcuffed to their base, and their base is wholly out of step with the rest of the country, living metaphorically on an island far away from the American mainland. Look at public opinion on the shutdown and the wall. By a two-to-one margin, Americans oppose shutting down the government to build pressure to fund the wall. Every major demographic group opposes the shutdown–except Republicans, who support it by a margin of 43 points. Independents and Democrats overwhelmingly blame Trump and congressional Republicans for the shutdown. Republicans blame congressional Democrats. On the Island, almost seven in ten Republicans say a wall will make a major difference in illegal immigration. On the mainland, only a small fraction agree.

With Donald Trump governing as President of Republican Island, and with Mitch McConnell acting as the Majority Leader of the Republican Island Senate, everything they do further alienates them and their party from the rest of the electorate and threatens further political retribution in next year’s general election. But they are trapped. Anything that would align them with the rest of the country, which wants a fully functioning government and a discussion of border security without a wall, would engulf the party in a conflict from which it might not recover. Having promised to seal off the country from imagined bands of multi-hued criminal marauders, Trump has no choice but to deliver. Except he can’t. Meanwhile, Senate Republicans choose to pretend he can, letting the closure continue indefinitely to avoid doing battle with their own supporters. This is not a strategy. But it is a tragedy, and readers of this blog have seen it coming for years.

There is no recent precedent for a political dynamic like Republican Island. It makes normal negotiations impossible, leaving Trump to make hollow demands for his wall while Republicans talk among themselves. Given their inability to step away from radically unpopular positions, Republicans have no way forward that leaves them in power and the country undamaged. It can be one or the other–or neither–but not both. There is no exit from the shutdown for Trump and McConnell that will allow the Republican Party to survive this moment unscathed. As they insist on holding power at all costs, there is no exit for the country either.