On the evening before the Nevadacaucus, a 67-year-old woman called Deborah Cole was having an emotional experience. 
Having driven 80 miles from her home in Mesquite, she was now at the Spring Reserve ampitheatre in Las Vegas as Bernie Sanders was about to speak. Her eyes barely flickered away from stage, and she grew passionate as she talked, especially when asked if she would vote for someone such as Michael Bloomberg if Sanders failed to secure the nomination. 
If the Democratic establishment wont let us have our candidate, Id rather vote green, she said. They think were stupid.
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In that exchange was contained the potential for both delight and disaster for Democrats, as they go about selecting a candidate to challenge Donald Trump. Sanders has established himself as the clear frontrunner after wins in Iowa, New Hampshire and Nevada, with the votes of young and enthusiastic supporters, much of if from people of colour.
Yet the passion those people feel for the 78-year-old from Vermont, extends much less to other Democrats seeking the nomination. Of supporters of all the candidates, those who back Sanders say they are less likely to vote for the Democratic nominee if it is not their man.
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Jessica Canicosa, a precinct captain for Bernie Sanders, waits to greet caucus voters at Liberty High School in Henderson, Nevada
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A supporter of Amy Klobuchar in Las Vegas, Nevada
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Hotel workers at the Bellagio in Las Vegas get to grips with voting papers during the Nevada caucuses
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Michael J Fox  the Back to the Future actor turned activist  speaks at a rally for Pete Buttigieg at Faiss Middle School in Las Vegas
5/25
Voters at a campaign event for Amy Klobuchar in Reno, Nevada
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A caricature of Bernie Sanders is projected on to a tree during a rally in Las Vegas
7/25
A woman waits to have a photo taken with Elizabeth Warren during a town hall meeting in Las Vegas
8/25
The threat of coronavirus and other germ-borne illnesses was on some voters’ minds at the Democratic caucuses in Henderson, Nevada
9/25
Former vice-president Joe Biden takes a selfie with a voter in Las Vegas ahead of the Nevada caucuses
10/25
A member of Mike Bloomberg’s election team in a campaign office in New York City
11/25
Amy Klobuchar changes her shoes backstage after giving a speech in Exeter, New Hampshire
12/25
A warmly-wrapped-up dog attends an Elizabeth Warren event at Amherst Elementary School in Nashua, New Hampshire
13/25
Bernie Sanders, who romped to victory in New Hampshire against Hillary Clinton in 2016, talks to the media in Manchester
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Lisa Olney, of Wellesley, Massachussets, demonstrates her support for Elizabeth Warren in Nashua, New Hampshire
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Joe Biden was hoping to improve on his poor showing in Iowa in the New Hampshire primary
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Elizabeth Warren, renowned for giving time to supporters for selfies, works the crowd at the University of New Hampshire in Durham
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Joe Biden takes a selfie with a supporter and his child outside a campaign event in Somersworth, New Hampshire on 5 February
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Elizabeth Warren and Bernie Sanders quarrel after a confrontation in a TV debate in which Sanders claimed that Warren was not telling the truth about a conversation in which she claimed he had said a woman could not win the presidency on 14 January
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Supporter Pat Provencher listens to Pete Buttigieg in Laconia, New Hampshire on 4 February
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Elizabeth Warren jogs away after speaking to reporters during a campaign event in Nashau, New Hampshire
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Supporters of Amy Klobuchar gather before a rally. Behind them, scores of Pete Buttigieg signs are planted in the snowy ground
22/25
Pete Buttigieg speaks at a campaign event in Concord, New Hampshire while awaiting the results of the Iowa caucus
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Elizabeth Warren is presented with a balloon effigy of herself at a campaign event in Nashua, New Hampshire on 5 February
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A Trump supporter rides past a rally for Amy Klobuchar in Des Moines, Iowa on 14 January
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A man holds up a sign criticising billionaires in the presidential race in front of Michael Bloomberg in Compton, Califronia. The former New York mayor skipped the first caucus in Iowa and instead campaigned in California on 3 February
1/25
Jessica Canicosa, a precinct captain for Bernie Sanders, waits to greet caucus voters at Liberty High School in Henderson, Nevada
2/25
A supporter of Amy Klobuchar in Las Vegas, Nevada
3/25
Hotel workers at the Bellagio in Las Vegas get to grips with voting papers during the Nevada caucuses
4/25
Michael J Fox  the Back to the Future actor turned activist  speaks at a rally for Pete Buttigieg at Faiss Middle School in Las Vegas
5/25
Voters at a campaign event for Amy Klobuchar in Reno, Nevada
6/25
A caricature of Bernie Sanders is projected on to a tree during a rally in Las Vegas
7/25
A woman waits to have a photo taken with Elizabeth Warren during a town hall meeting in Las Vegas
8/25
The threat of coronavirus and other germ-borne illnesses was on some voters’ minds at the Democratic caucuses in Henderson, Nevada
9/25
Former vice-president Joe Biden takes a selfie with a voter in Las Vegas ahead of the Nevada caucuses
10/25
A member of Mike Bloomberg’s election team in a campaign office in New York City
11/25
Amy Klobuchar changes her shoes backstage after giving a speech in Exeter, New Hampshire
12/25
A warmly-wrapped-up dog attends an Elizabeth Warren event at Amherst Elementary School in Nashua, New Hampshire
13/25
Bernie Sanders, who romped to victory in New Hampshire against Hillary Clinton in 2016, talks to the media in Manchester
14/25
Lisa Olney, of Wellesley, Massachussets, demonstrates her support for Elizabeth Warren in Nashua, New Hampshire
15/25
Joe Biden was hoping to improve on his poor showing in Iowa in the New Hampshire primary
16/25
Elizabeth Warren, renowned for giving time to supporters for selfies, works the crowd at the University of New Hampshire in Durham
17/25
Joe Biden takes a selfie with a supporter and his child outside a campaign event in Somersworth, New Hampshire on 5 February
18/25
Elizabeth Warren and Bernie Sanders quarrel after a confrontation in a TV debate in which Sanders claimed that Warren was not telling the truth about a conversation in which she claimed he had said a woman could not win the presidency on 14 January
19/25
Supporter Pat Provencher listens to Pete Buttigieg in Laconia, New Hampshire on 4 February
20/25
Elizabeth Warren jogs away after speaking to reporters during a campaign event in Nashau, New Hampshire
21/25
Supporters of Amy Klobuchar gather before a rally. Behind them, scores of Pete Buttigieg signs are planted in the snowy ground
22/25
Pete Buttigieg speaks at a campaign event in Concord, New Hampshire while awaiting the results of the Iowa caucus
23/25
Elizabeth Warren is presented with a balloon effigy of herself at a campaign event in Nashua, New Hampshire on 5 February
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A Trump supporter rides past a rally for Amy Klobuchar in Des Moines, Iowa on 14 January
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A man holds up a sign criticising billionaires in the presidential race in front of Michael Bloomberg in Compton, Califronia. The former New York mayor skipped the first caucus in Iowa and instead campaigned in California on 3 February
Such loyalty is displayed not just conversations with people such as Cole, an accountant, but by several polls. One carried out in by Emerson Polling suggested only 53 per cent of current Sanders supporters said they will definitely support the eventual nominee. 
In contrast, at least 85 per cent of Joe Biden, Pete Buttigieg, and Elizabeth Warren supporters said they would vote whomever the party nominated.
In interviews with Sanders supporters The Independent found the candidate most acceptable as a second choice was Elizabeth Warren, while the least acceptable was former New York mayor Michael Bloomberg. 
At the get out the vote rally on Friday, one couple disagreed fundamentally on this very issue. Shaun Richards said while did did not like the billionaire businessman, he would vote for anyone to try and and stop Trump. His partner, Jacqueline Bunge, said she could not bring herself to vote for Bloomberg, who aroused in her strong emotions and stern words.
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Why does this matter? In 2016, many supporters of Sanders were horrified at the prospect of voting for Hillary Clinton, who many believed was in the pay of Wall Street. 
Some said they would vote for down ticket candidates senators and congressman and such like on election day, and leave blank, or write the name of Sanders, where the ballot paper said Hillary Clinton. Some said they would vote for Trump, who at that time was presenting himself in terms not entirely dissimilar to Sanders, as someone who was not part of the establishment and would clean up the system.
In the end, angered about the way some within the Democratic National Committee had sought to undermine Sanders and support Clinton revealed by hacked DNC emails published by Wikileaks and by presence of super delegates who gave crucial backing to Clinton, plenty could not bring themselves to support her. 
To his credit, at at the partys convention that summer in Philadelphia, Sanders did his duty in urging his supporters to now back Clinton. 
Bernie Sanders wins Nevada primary
I understand many people here in this convention hall and around the country are disappointed about the final results of the nominating process. I think its fair to say that no one is more disappointed than I am, he said in one of the most powerful speeches of the political cycle.  
[But] this election is about and must be about the needs of the American people and the kind of future we create for our children and grandchildren.
It was not enough. Polls suggest as many as 12 per cent of people who voted for Sanders in the primary, went for Trump in the general election. Given he only won the White House by 77,000 votes scattered across three states Wisconsin, Michigan and Pennsylvania it is impossible to know the impact of such defections.
These are emotional, sensitive matters and people need to choose their language with care. Supporters of Sanders are angry when backers of other candidates accuse them of being potential wrecking balls in November.
Their opposition to the likes of Bloomberg, who has spent $400m of his estimated $63bn fortune to self-fund his campaign, while Sanders has built his with the support of small donation from ordinary people, most commonly teachers, is understandable. 
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On Friday night, Sanders said his campaigns average donation was just $18.53. He said he received cheques from employees at Walmart and Amazon, people who are earning low wages but who send 20 bucks or so to help bring change.
And much of what Sanders says about the state of America is undeniably true. Inequality is vast and getting worse, the healthcare system is wasteful and inefficient, and too many people use GoFundMe campaigns to fund their healthcare. 
In cities such as San Francisco and Seattle, where corporations such as Amazon escape paying federal taxes, homelessness is out of control. People in tents gather under flyovers and new construction. The criminal justice system, by any measure, discriminates hugely against people of colour.
As supporters of Sanders correctly point out, all of this means the stakes have never been higher. 
It also means Bernie Sanders needs to think very carefully what he will tell his supporters if he does not win the race he is currently leading.