Former Vice President Joe Biden Thursday night told a gathering of rich donors that the Labour Party's crushing defeat in the U.K. general election represents a warning sign that Democrats should not nominate a left-wing candidate in 2020, a narrative progressives immediately condemned as highly misleading and pernicious.

"Suffice it to say that 'Boris is kind of like Trump and Corbyn is kind of like Sanders so tonight's results mean that Sanders would be a bad nominee' is a profoundly silly and unserious take."

—Angus Johnston, City University of New York

"Look what happens when the Labour Party moves so, so far to the left," Biden, a 2020 Democratic presidential candidate, told donors at a fundraiser in San Francisco Thursday. "It comes up with ideas that are not able to be contained within a rational basis quickly."

"You're also going to see people saying, 'My God, [U.K. Prime Minister] Boris Johnson, who is kind of a physical and emotional clone of the president, is able to win," the former vice president said, according to pool reports.

Biden's remarks mirrored the immediate post-election reaction of centrist pundits on Twitter late Thursday as exit poll results made clear that Labour, led by Jeremy Corbyn, lost decisively.

"Warning from across the pond to Dems flirting with Bernie/Warren," tweeted National Journal politics editor Josh Kraushaar, referring to leading 2020 Democratic presidential contenders Sens. Bernie Sanders (I-Vt.) and Elizabeth Warren (D-Mass.).

Oh gawd. Here we go with the "left can't win" takes. The UK political situation while similar in some ways to the US is also massively different to the US on so many other levels. For a start, the US isn't trying to leave the EU. Anyways, the UK result depressing all round... https://t.co/GFAOCM9LQg — Mehdi Hasan (@mehdirhasan) December 12, 2019

Kraushaar's argument, echoed by many on social media, was soon expressed in Friday morning news headlines and television programs.

"Bernie consistently polls better than Trump, is extremely popular, and there's no analogous issue to Brexit."

—Christo Aivalis, historian

"Corbyn's U.K. defeat was bad news for Sanders, Warren, and America's left," blared NBC News's "First Read" headline on the U.K. election results.

"Last night's election showed the limits of campaigning and winning on ideology," wrote NBC's Chuck Todd, Mark Murray, and Carrie Dann. "A socialist or very left-leaning message—inspired to turn out young voters and unite the working class—simply didn't work."

In his "Reality Check" segment Friday morning, CNN's John Avlon stated, as if it were a political truism, that "right-wing populism beats left-wing populism."

"Democrats should be paying close attetion to the Labour Party's brutal beating in the U.K. elections last night because it's a cautionary tale as they prepare for the 2020 primaries," said Avlon. "Polls shows that Labour should have been poised to take back 10 Downing Street. But they decided to stick with an unreconstructed socialist, Jeremy Corbyn."

Democrats should pay close attention to the Labour Party’s brutal beating in the UK elections last night, says @JohnAvlon — because it is a cautionary tale as they prepare for the 2020 primaries. https://t.co/x3wszD1aJe #RealityCheck pic.twitter.com/kxLfBEFCN3 — New Day (@NewDay) December 13, 2019

Progressives and other critics were quick to push back against efforts to use Corbyn's loss as a cudgel against Sanders and Warren, noting that unique political dynamics in the U.K.—particularly polarization over Brexit and Corbyn's deep unpopularity—make such comparisons absurd and dishonest.

Speaking to reporters in the Oval Office on Friday, Trump himself seized on the U.K. election as a possible "harbinger of what's to come in our country."

"It was last time," Trump said, referring to the British public's vote to leave the European Union just months before the 2016 U.S. presidential election.

Commentators were quick to note that, unlike Corbyn against Johnson, Sanders has polled favorably against Trump in hypothetical general election match-ups.

In a sharply-worded video post online late Thursday night, historian and political observer Christo Aivalis offered a point-by-point rebuttal to anyone trying to use Corbyn's defeat as an attack on Sanders.

"Bernie consistently polls better than Trump, is extremely popular, and there's no analogous issue to Brexit," explained Aivalis.

Watch:

"Comparisons to the U.K. are inevitable but lazy," said Adam Jentleson, public affairs director at advocacy group Democracy Forward. "If you're gonna do it, you have to grapple with the fact that Corbyn was deeply unpopular whereas Biden, Bernie, and Warren all rank about the same on fav[orability]."

Angus Johnston, professor at the City University of New York, also pointed out that Sanders' overall favorability rating among the U.S. electorate is far higher than Corbyn's in the U.K.

"Suffice it to say that 'Boris is kind of like Trump and Corbyn is kind of like Sanders so tonight's results mean that Sanders would be a bad nominee' is a profoundly silly and unserious take," Johnston wrote in a series of tweets Thursday night.

Bernie Sanders approval rating average: -3.

Donald Trump approval rating average: -11.

Boris Johnson approval rating average: -12.

Jeremy Corbyn approval rating average: -40. — Angus Johnston (@studentactivism) December 13, 2019

The Intercept's Glenn Greenwald wondered why "Corbyn's defeat in Brexit-complicating U.K. proves the left can't win in U.S., but the stunning victory by Argentina's leftist Fernandez/Kirchner ticket doesn't show undiluted leftism is necessary to win?"

"Maybe people are manipulating inapplicable results for their own ends?" said Greenwald. "If you're going to exploit foreign election outcomes to try to bolster your own ideological preferences in the U.S., try not to be so glaringly selective in how you do it. The left is winning in many places; you need to grapple with those victories, too."