After five years in the United States, I have returned to a Great Britain that I barely recognize.

Domestic British politics has been hijacked by Scottish and English nationalists. In foreign affairs, Britain is now semi-detached from the European Union but is no closer to the United States, or anywhere else, as a result. And Jeremy Corbyn last month pulled off perhaps the biggest political coup in Europe. A lifelong outsider and insurgent, Corbyn suddenly captured the leadership of one of the two pillars of the British political system, the Labour Party.

Thomas de Waal De Waal is a senior fellow with Carnegie Europe, specializing in Eastern Europe and the Caucasus region. More > @Tom_deWaal

The same forces of revolt that have spurred Britain’s political crisis have propelled socialist Bernie Sanders into striking distance of Hillary Clinton in the battle for the Democratic Party’s nomination. The new challengers share a distrust of “the establishment” and the belief that the outmoded institutions of politics deserve to be stormed like the Bastille in the revolutionary Paris of 1789.

Sanders is unlikely to follow in Corbyn’s footsteps and snatch control of a major political party. That’s not just because of Sanders’ recent underwhelming debate performance — it’s because Britain’s political malaise is in a more advanced stage than that of the United States. But the fact that Sanders and fellow political insurgent Donald Trump have done as well as they have is evidence that the once-venerated institutions of America, like those of Britain, are beginning to smell of mold.

The Sanders and Trump candidacies are electoral spasms of the U.S. body politic as it adjusts to America’s reduced power and respect in the world. The rebels do not have convincing answers to the challenges before their country. Trump’s slogan, “Make America Great Again,” should be read not as a triumphant declaration of the return of U.S. prestige but as a sign of America’s refusal to face the fact that its former place as the world’s sole superpower is gone and isn’t coming back.

There are lessons for America to draw from Britain, which has been adjusting to a similar fall from greatness over the past century.

Britain used to think of itself as an indispensable country. The British classic 1066 and All That, a parody of a school textbook, mines a humorous seam from the idea that for the entire length of modern history Britain was “Top Nation,” fighting off efforts to wrest away that status by dastardly foreigners, from Philip II of Spain to Napoleon. With the end of World War I and the Treaty of Versailles, the book ends because “AMERICA was thus clearly top nation, and History came to a .”

Britain has spent the last few generations working out the meaning of the residual truths of that cliché. That means we recognize the debates in the U.S. media about whether the United States is “losing its leadership in the world” or “in decline.”

Of course, the “decline” debate is massively oversimplified. Global politics is not a sporting competition, and being a citizen of a country that is objectively less “great” than it used to be, brings a certain useful humility. Britain has shed a lot of its pomposity — while America’s ego remains overinflated. Indeed, I witnessed the “world-revolves-around-us” self-importance Britain has mostly shed at certain think-tank panel discussions or breakfast conversations in Washington.

In 2012, NBC totally failed to notice the changed Britain, when it chose to air mini-documentaries about the Blitz and “Downton Abbey” just before the Opening Ceremony of the Olympics in London. This replicated a stereotype Americans still feel comfortable with, of Britain playing the elderly dowager countess to America’s young democrat. But the ceremony itself then showcased a very different multicultural Britain that is worlds away from “Downton Abbey,” celebrating institutions such as Britain’s National Health Service, the model of universal health care.

Post-imperial Britain is also ahead of the United States on issues such as combating climate change — although living on a small crowded island may have a lot to do with that. (I think you can understand almost everything about our two nations if you consider that the most beloved radio program on the BBC is “Gardeners’ Question Time,” while on NPR it is “Car Talk”).

And yet over the last couple of decades, Britain’s political class has ducked the big challenge of reconfiguring the country’s role in international affairs and reinventing domestic political institutions — issues that the United States must face up to as well.

The paradox is that two countries, which are so inter-connected with the rest of the world through business, trade, science and technology, are at the same time so politically old-fashioned.

For too long, many on both sides of the Atlantic have shared the assumption that, just as surely as its clocks align themselves to Greenwich Mean Time, the world’s default political system is Anglo-Saxon democracy. Both countries have regarded themselves as “leaders,” not “joiners.” But what happens when the rest of the global order no longer heeds your leadership?

Prime Minister David Cameron is putting the idea of an indispensable Britain to a dangerous test, as he has called a referendum on the country’s continued membership of the European Union, probably to be held next year. His position is that a Yes vote is dependent on the EU’s readiness to “repatriate” powers to Britain. But Cameron is worryingly imprecise on what he expects and what Brussels should deliver. It is, in short, a gamble. The outcome will at best confirm Britain’s status as a semi-detached member of the EU or, at worst, lead to a “Brexit” — a British exit from the Union into even greater international isolation.

If Brexit does occur, Scottish Nationalist Party leader Nicola Sturgeon says that she wants another independence referendum in which Scotland could leave the United Kingdom and seek to rejoin the EU — thereby leaving England broken not just from Europe but from Scotland as well.

Britain’s insurgents are no more enlightened on foreign affairs. On the other side of the political ledger, Labour’s improbable new leader, Corbyn, has even more dangerous isolationist instincts. He is skeptical of the EU, hostile to NATO and the United States and would basically have Britain walk off the world stage altogether.

This is a problem greater than Cameron or Corbyn. It is a reminder that in the 1970s and 1980s, when Britain was still in love with exceptionalism, it missed the challenge to shape the EU from inside and make it a more dynamic institution with more of an Anglo-Saxon character and less Gallic bureaucracy.

Britain’s crisis stems in large part from the principle, “That’s how we’ve always done it and it’s made Britain great.” That belief has become a hollow credo while the world has moved on.

Does that sound familiar?

For Britain’s dysfunctional relationship with the EU, read the United States’ relations with world multilateral organizations in general.

After years of American exceptionalism, based on the assumption that “the world will follow our lead,” American political leaders are now facing the question: “What if they don’t?” In retrospect, the immediate post-Cold-War period looks like a missed moment, when the United States looked out at a world containing a dynamic EU, a cooperative Russia and a not-yet assertive China — but did almost nothing to institutionalize that order.

The 1990s were surely the moment for the United States to work with the EU to strengthen the world’s multilateral normative institutions, beginning with the United Nations (FDR’s project), to sign the Kyoto Protocols and join the International Criminal Court. The United States cannot even join the Law of the Sea Convention or the international treaty against landmines. But had Washington led the way on issues like these, there would be more a rule-based international order to confront the challenges thrown down now by China and Russia.

This excessive veneration of the past is also a key reason why the domestic political establishment is facing an uprising in both countries.

Take the key determinant of the health of a democracy — the system it uses to elect its leaders. Both Britain and the United States rely on a “first-past-the-post,” winner-takes-all system which dates at least 300 years in Britain.

In Britain, that system is now delivering strange election results that mean most voters are not getting remotely what they ask for. For much of the 20th century, first-past-the-post reflected more or less fairly the dominance of two parties: Conservative and Labour. Those days are gone and modern-day Britain is now a multiparty society with a two-party electoral system. That meant that in the general election in May, three parties — UKIP, the Liberal Democrats and Greens — won between them a quarter of the national vote and 7.5 million votes but received collectively only 10 seats in the 650-seat House of Commons.

The outcome is badly hurting the country’s belated attempts to redistribute power among the nations and the regions of the United Kingdom. The general election excluded sullen English nationalists but also over-compensated Scot nationalists. In Scotland, the same system ensured that the Scottish National Party won 1.5 million votes (around half of the vote) but captured 56 of Scotland’s 59 seats.

This democratic car crash could have been avoided a generation ago if our rulers had faced up to the task of figuring out a fairer electoral system and decentralized government. Britain has only recently acquired local parliaments for Scotland, Wales and Northern Ireland, while many major English cities still do not have elected mayors. Many citizens, particularly in England, feel disenfranchised. And yet, the ruling political class still praises Britain as a model of democracy and Westminster as “the mother of parliaments.”

Do you recognize this scenario, United States in the era of Trump and Sanders? At some point, possessing an unbalanced electoral system, where a large number of voters feel their vote is meaningless, can become a real threat to democracy. And once they view politicians not as their democratic representatives but as the ancien regime, some of them start to begin to build barricades.

It takes only a brief acquaintance with Washington to understand that U.S. political institutions are broken from the Congress and the politicized judiciary to the electoral system and its gerrymandering. Everyone knows this — and indeed comments on it — but somehow fixing the problem is always a low priority.

This may be because a dysfunctional system is never inclined to repair itself. But another reason is a strange reluctance to modernize the institutions of state.

Consider the Senate, crippled by archaic practices such as the filibuster, conceived with different aims in an entirely different era, but which now every president has to overcome as he tries to make elementary appointments to staff government or pass legislation that already has majority support. Archaic practices like these undermine public confidence in Congress, creating a vacuum that is then filled by the anti-establishment insurgents.

The Founding Fathers were wise men. They also were the modernizers of their time, who would surely be shocked to see their prescriptions for 18th century America still being invoked two-and-a-half centuries later. A constant appeal to their wisdom makes the country less a democracy than a secular theocracy.

It is never too late to change. In both countries the political elite is perfectly capable of imagining the new and not just curating the old. But a lesson from no-longer-top-nation Britain is that it would have been so much easier to reform those old institutions that are no longer so “fit for purpose” in quieter times than these. Now, it is like trying to fix the brakes of the bicycle when you are already speeding downhill.

This article was originally published in POLITICO Europe with the title “The hijacking of Anglo politics”.