Bernie Sanders supporters have not taken well to Massachusetts senator Elizabeth Warren’s endorsement of Democratic presumptive nominee Hillary Clinton, with many arguing that it would seriously undermine Warren’s reputation as a champion of progressives and the working people of America.

On Thursday night, Warren voiced her endorsement of Hillary Clinton on MSNBC’s Rachel Maddow Show, saying that she was “ready to jump in the fight” and stop Donald Trump from getting anywhere near the White House.

“I’m ready. I am ready to get in this fight and work my heart out for Hillary Clinton to become the next president of the United States — and to make sure that Donald Trump never gets anyplace close to the White House,” Warren said.

Warren’s endorsement of Clinton came as a surprise to many, including a major chunk of Bernie Sanders’ supporters. The Massachusetts senator’s longstanding criticism of the increasing influence corporate America has come to exert in molding the country’s economic policies aligned her particularly well to Sanders’ position on Wall Street reforms, and when Sanders’ campaign was still in its nascent stages, many had even speculated on the possibility of the Vermont senator eventually picking Warren as his running mate if he won the Democratic nomination.

Moreover, Elizabeth Warren has also been critical of Hillary Clinton’s alleged patronage of big banks and American financial juggernauts through the course of her political career, and in 2004, she had even called then-senator Clinton a “puppet” for corporate America.

But not only has Warren forsaken those criticisms to side with Hillary Clinton in the presidential race, ABC News now reports that Warren paid Clinton an extended visit Friday morning, fueling speculations that Clinton might be considering picking the Massachusetts senator as her running mate.

Even on social media, Warren has taken to lashing Donald Trump and echoed Clinton’s demand that Trump delete his account on Twitter Friday morning.

Elizabeth Warren: Trump does exactly what you'd expect "from a thin-skinned, racist bully" https://t.co/9vorLYn0ZU https://t.co/ytcCa1dkoD — CNN (@CNN) June 9, 2016

No, seriously -- Delete your account. https://t.co/O1u7oc0jAR — Elizabeth Warren (@elizabethforma) June 10, 2016

While some of Warren’s supporters see her endorsement of Clinton as necessary to stop Donald Trump from claiming the Oval Office come November, several others believe that Elizabeth Warren has betrayed her progressive agenda by siding with someone whom they essentially see as a corrupt and warmongering political leader.

As Vox reports, Warren’s Facebook page “erupted with rage and disappointment from Bernie Sanders supporters” after news of her endorsing Hillary Clinton poured in.

(Image via Elizabeth Warren/Facebook)

(Image via Elizabeth Warren/Facebook)

The disgruntled supporters are not only making their voices heard on Facebook. Even on YouTube, a chunk of Bernie Sanders’ supporters vented their ire on Warren’s decision to endorse Hillary Clinton. While many called on her to reconsider her decision, others termed her a “sellout,” a “pseudo progressive neoliberal,” and one commenter even suggested that she was similar to a “parasite” who displayed “gross opportunism” in deciding to support Clinton.

According to the Hill, it is not only Bernie Sanders’ supporters who are critical of Elizabeth Warren, but even Sanders’ surrogate and former Ohio state senator Nina Turner lashed out at her, saying that the Massachusetts Democrat has not done enough for the progressive cause.

“It’s easy for Democrats to attack Mr. Trump. You don’t get any brownie points from me and other progressives for getting into a Twitter war with Mr. Donald Trump. That’s easy. “But when the fight was hard for Sen. Bernie Sanders, where was Sen. Warren?”

It is quite clear that Elizabeth Warren’s endorsement of Hillary Clinton has taken several Democrats, including her supporters, by surprise. While it may well be an act of political reconciliation on her part, for Bernie Sanders’ supporters, it is simply an act of betrayal that might disillusion them further with the Democratic nominating process this election season.

[Photo by Alex Wong/Getty Images]