Does the bolt of eight members of Parliament from the British Labour Party out of frustration with its left-wing leader, Jeremy Corbyn, have anything to teach Democrats in the United States?
There's a case for saying no, since Corbyn is well to the left of anyone bidding to lead the Democratic Party. That would include Sen. Bernie Sanders, the democratic socialist who announced Tuesday that he's again seeking the presidency. The independent from Vermont is a lefty for sure, but his worldview is rooted in less radical forms of socialism than Corbyn's, and his foreign policy views are somewhat more conventional than the Labour leader's.
Competing with Sanders for support from the democratic left is Sen. Elizabeth Warren, D-Mass. She proudly insists that she's a capitalist, a boast that would make Corbyn shudder.
Moreover, a core beef of the center-left British rebels has to do with Corbyn's handling of Brexit, an issue that -- mercifully -- the United States does not have to deal with.
Most Labour Party moderates, and the vast majority of its members, want their leadership to push hard for a second referendum to reverse the country's narrow 2016 decision to leave the European Union. But Corbyn is well-known to be, at best, ambivalent about membership in the EU (he opposed it in the past as a capitalist club) and has, up to now, not made a second referendum central to his strategy.
Corbyn's critics like to say he's had a "bad Brexit," by which they mean that he has failed to take advantage of Prime Minister Theresa May's chaotic performance. Her complex approach to leaving the EU has suffered one parliamentary defeat after another and split her Conservative Party.
Indeed, the revolt of the pro-Europe center broadened on Wednesday when three Conservative MPs quit their own party to join the new Independent Group.
Yet Corbyn-led Labour has not opened anything like the large advantage in the polls that an opposition ought to have in these circumstances.
A particular flashpoint is Corbyn's lack of real energy or clarity in confronting an outbreak of left-wing anti-Semitism. This was the prime motivation behind MP Luciana Berger's decision to leave the party. Berger, who is Jewish, has been treated barbarously by some on the "Brocialist" left.
"I cannot remain in a party that I have come to the sickening conclusion is institutionally anti-Semitic," Berger said. On Tuesday, an eighth Labour parliamentarian, Joan Ryan, joined the flight, citing a "culture of anti-Jewish racism" in the party she's belonged to for four decades.
So why should Democrats in the United States care about any of this?
Begin with the fact that Labour and the Democrats have historically had a lot in common as reformist center-left parties. President Bill Clinton and British Prime Minister Tony Blair were close allies in creating a middle-of-the-road politics that sought to accommodate the left to the market rhythms of the Reagan and Thatcher Eras. Blair's "New Labour" in the mid-1990s echoed Clinton's "New Democrats" from a few years earlier.
But the "neo-liberalism" the left associates with Clinton and Blair came under fierce progressive assault after the 2008 economic implosion for being too financier-friendly, insufficiently attentive to rising inequality, and too confident in the benefits of free trade and deregulation. The backlash in Britain was particularly vigorous in response to Blair's strong support for President George W. Bush's invasion of Iraq.
Again, whatever Republicans may claim, Democrats are a long way from embracing Corbynism. But the bitterness of the growing divide between the left and center-left in Britain is a warning of how debilitating intra-progressive strife could become in Congress and in the 2020 primaries.
Given that the defeat of Donald Trump is the absolutely necessary first step toward a more humane politics, more moderate and more adventurous Democrats can ill afford to concentrate their fire on each other. The stakes are too high for self-indulgent sectarianism.
And differences in approach over how to guarantee everyone health coverage or how to fight climate change are less important than agreeing that both problems are urgent and need solving. Remembering that your opponents would prefer to do nothing at all on these issues is a good way to put such disagreements into perspective.
It's an irony of recent Labour Party history that both Blair and Corbyn invoked a commitment to stand up for "the many, not the few" as the battle cry of their very different campaigns. Nothing makes the privileged few happier than a left that becomes too maximalist to win, and then tears itself apart.
E.J. Dionne wrote this piece for The Washington Post.