The movement is called “Bernie or Bust,” and it means just that: If Sen. Bernard Sanders of Vermont loses the Democratic presidential nomination, a group of his supporters will either write in his name in the general election or consider casting their ballot for a Republican.

The one thing they certainly won’t do: Vote for Hillary Clinton.

More than 50,000 people already have signed up at the Revolt Against Plutocracy, pledging to vote for the Green Party candidate in the general election or write in Mr. Sanders’ name if Mrs. Clinton wins the Democratic nomination. Other groups, such as Grassroots Action for Bernie, are taking to social media, using Facebook and Twitter to try to get the “Bernieorbust” hashtag trending.

SEE ALSO: Hillary Clinton routs Bernie Sanders in the South, moves closer to nomination

Even Sanders supporters not tied to the movement, or unaware of its existence, seem to agree with its principles, making one thing clear: The Democratic National Committee and Mrs. Clinton will have a hard time attracting many of Mr. Sanders’ voters.

“I will not be voting for Clinton if Sanders does not win the nomination,” said Jon Clemens, a Sanders supporter from Hartford, Connecticut. “She has done nothing to earn my vote, and the Democratic Party should not assume that she will simply absorb Sanders’ supporters. Clinton has only ‘evolved’ to progressive political stances when public polling indicated to her that it was politically advantageous to do so. She is disingenuous, has little integrity and lacks vision.”

As Mrs. Clinton gets closer to sewing up the nomination, her campaign will begin to grapple with damage from an increasingly divisive fight with Mr. Sanders.

SEE ALSO: Sanders out-raises Clinton by more than $10M in February

Mrs. Clinton spent much of the primary contest tacking to the left to try to blunt Mr. Sanders’ attacks, but the senator’s supporters say her late-season political conversion isn’t convincing.

“We Bernie fans just won’t vote for her,” said Steph Faulkner, who hails from Mr. Sanders’ home state of Vermont and is an avid Sanders supporter. “We are sick of the media telling us we have too. We don’t like her. We don’t trust her. We believe she is a Wall Street puppet. There is nothing they can say that will make us vote for such a woman. I mean, heck, people would vote for Trump over her, and he is a monster. What does that tell you? It tells me she is seen as the bigger evil. Trump is less evil than Hillary.”

Part of the equation for Mrs. Clinton and other Democratic leaders is how widespread that sentiment is within their political base. Sanders supporters say not to underestimate them.

“More than 50 percent of Sanders supporters will never vote for her,” Chris Fox, a Sanders supporter in Fairfield, Ohio, said in an email. “That is why she will not beat Trump. Weigh the Republican hate for her (motivation to vote) against the Democrat progressive liberal’s hate for the status quo (unmotivated to vote for her), and we have a major problem on our hands. Only Sanders can beat Trump, but that’s not why we are voting for him. He’s the only person we trust with the job.”

The sentiment was by no means universal. At the polls Tuesday, a number of Sanders supporters told The Washington Times that despite tension between Mrs. Clinton and Mr. Sanders, they would vote for the former secretary of state if only to stop Republicans.

“Any of the Republicans would move us more toward the killing of civilians and a more interventionist foreign policy than what we’ve seen from the Obama administration,” said a 30-year-old woman voting in Atlanta.

For some Sanders voters, their decision in November will depend on Republicans. The prospect of businessman Donald Trump winning the Republican nomination and facing off against Mrs. Clinton would force many of the Sanders supporters into Mrs. Clinton’s camp.

Steve Herbert, a technology consultant voting in Atlanta, who called Mrs. Clinton “wishy-washy” on major political issues, said he would have to back her in a race against Mr. Trump, but it would be a tossup if she faced any other Republican.

“It depends on what comes out on the other side,” Mr. Herbert said.

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