Great Britain used to be the most powerful nation on Earth.

Now it seems powerless to govern itself.

A paralyzed Parliament is still unable to execute — or kill off, via a second referendum — Brexit three years since British voters shocked the world and perhaps even themselves by voting to leave the European Union.

The latest failures are at the foot of Boris Johnson, Britain’s new prime minister, who played constitutional hardball only to get brushed back by a broad coalition of lawmakers, including 21 from his own Conservative Party.

Together, these members of Parliament, mostly led by the Labour Party, made a mad dash to block a “no-deal” Brexit before Johnson could suspend — or “prorogue,” in dignified parliamentary parlance that didn’t match the maneuver’s shabbiness — Parliament before the Oct. 31 deadline.

Johnson, who on Thursday said that he would rather be “dead in a ditch” than seek another E.U. extension, may be politically expired after he lost his governing majority in dramatic fashion. On Tuesday, Tory MP Phillip Lee literally and politically walked over to join centrist Liberal Democrats, who resolutely oppose Brexit. Johnson purged others — including, poignantly, Winston Churchill’s grandson Nicholas Soames, who served for 37 years. And on Thursday, Johnson’s brother Jo resigned, citing “unresolvable tension” between “family loyalty and the national interest.” Family matters are one thing; national matters are another. Brexit could rekindle Scottish succession fever and even perhaps a return of the “Troubles” in Northern Ireland.

Johnson’s call for a snap election was blocked, at least until the Brexit deadline is resolved. A vote looms soon, although many Brits dread choosing between a beleaguered Johnson and Labour leader Jeremy Corbyn, whose quasi-socialist policies may be as damaging as Brexit’s self-inflicted wounds.

“The outcome of an election is very uncertain,” Amanda Sloat, senior fellow at the Brookings Institution’s Center on the United States and Europe, told an editorial writer via e-mail. “Voters will be asked to cast a ballot that reflects their views on Brexit, domestic policies for the next five years, and party leader — leading to complicated and sometimes contradictory preferences.”

Characteristically, President Donald Trump rallied around Johnson despite damage already done to Western unity. And Vice President Mike Pence added to the friction when he called on the E.U. to “negotiate in good faith,” as if E.U. leaders have not been forthright.

Trump and Pence shouldn’t be so reflexively defensive of Brexit. They should consider the words of Lee, who said upon switching parties that “this Conservative government is aggressively pursuing a damaging Brexit in unprincipled ways. It is putting lives and livelihoods at risk unnecessarily, and it is wantonly endangering the integrity of the United Kingdom.

“More widely, it is undermining our country’s economy, democracy and role in the world. It is using political manipulation, bullying and lies. And it is doing these things in a deliberate and considered way.”

That’s the sad reality of how Brexit, and Boris Johnson, are diminishing a once-great nation.