Responding to the results of the U.K. election, which commentators have already deemed a "political upset" for the ages and a stunning backfire for Prime Minister Theresa May, Sen. Bernie Sanders (I-Vt.) on Thursday congratulated Labour leader Jeremy Corbyn and the British people for "rising up against austerity and massive levels of income and wealth inequality."

"Globalization has left far too many people behind." —Sen. Bernie SandersPeople "all over the world" are fighting the same battle, Sanders added, concluding:

People in the U.K., the U.S. and elsewhere want governments that represent all the people, not just the 1%. I congratulate Jeremy Corbyn for running a very positive and effective campaign.

Corbyn's strong run—which culminated in an additional 31 seats for Labour and a hung parliament—was, in many ways, reminiscent of the Sanders "revolution" in the United States, which posed a stark challenge to "the billionaire class" and a political establishment flush with corporate money. Sanders himself drew the comparison between his campaign and Corbyn's recently on a three-day U.K. speaking tour, during which he praised the Labour leader's "willingness to talk about class issues."

"These problems are not unique to the U.S.," Sanders noted. "Globalization has left far too many people behind. Workers all over the world are seeing a decline in their standard of living. Unfettered free trade has allowed multinational corporations to enjoy huge profits and make the very rich even richer while workers are sucked into a race for the bottom."

Corbyn utilized similar messaging. Under his leadership, the Labour Party this year published one of the most left-wing manifestos in its history, adopting a slogan Sanders backers surely recognized: "For the many, not the few."

It is unsurprising, then, that British voters were seen donning Sanders apparel as they cast their ballots for Labour.

Peter Bloom, writing for Common Dreams, argued the campaigns of Sanders and Corbyn both successfully harnessed similar forces, and thus "exposed the beginnings of a potentially new political mainstream."

Bloom concluded:

Corbyn's strong campaign is no small political achievement. Historically, he has altered the public discussion on major issues of the economy and foreign policy. He has also shown that a full throttled progressive agenda is not only not suicidal but potentially downright popular.

For many, Corbyn's remarkable surge in recent weeks and his performance in an election that was prematurely viewed as a landslide opportunity for the Conservatives is a strong indicator of the electoral viability of left populism and of the strong desire for systemic change.

Corbyn is way to the left of Bernie, smeared more by the media (& Bernie has way more legislative accomplishments). Bernie would have won. — Lee Fang (@lhfang) June 9, 2017

UK voters weren't voting against the US President; they came out to vote FOR progressive policies that build a better future for their kids. https://t.co/bcV9Et2BIe — Our Revolution (@OurRevolution) June 9, 2017

LONG lines of young voters all across U.K. As w/@BernieSanders, @jeremycorbyn draws a new generation to the polls.https://t.co/bGtrPw6ny9 — John Nichols (@NicholsUprising) June 8, 2017

Pollsters and analysts—even those who had for weeks closely documented Corbyn's rapid rise in the polls—were openly startled by the results.

"No major left-wing politician had been so often accused of being unelectable—not even Sanders," wrote the Washington Post's Dave Weigel. "All through election night, the BBC and other organs of an infamously Corbyn-skeptical media marveled at how Labour had gained ground."

In a triumphant rally on Thursday, Corbyn argued that his party's gains portend a seismic shift in the landscape of British politics.

"Politics has changed," Corbyn declared as the results rolled in. "Politics isn't going back into the box where it was before. What's happened is people have said they've had quite enough of austerity politics."