Santa Ana, California (CNN) Edgar Garcia decided in 2016 to support Bernie Sanders . In the four years since -- as other candidates came along with similar plans and arguments about how they could beat Donald Trump -- he never wavered.

The 20-year-old student fervently believes Sanders is the only candidate who can build a coalition to defeat the President.

"He's going to bring out the votes of most of the young people, because every other Democratic candidate doesn't pull anyone I know, especially coming from a Hispanic background," he told CNN here during a Sanders rally on the eve of the Nevada caucuses . "I know a lot of people who are Hispanic who are really excited to come out and vote for him."

Garcia predicted Sanders would also turn out "the people Hillary Clinton turned her back on; the people in Pennsylvania and the Rust Belt. Bernie Sanders will be able to get their vote, even if they voted Republican."

Scores of interviews with Sanders supporters over the past year underscore the fierce loyalty of his supporters. They feel the Vermont senator is channeling their frustration about the injustices foisted on the working class. They are bound to Sanders through a covenant of trust that he will be their unwavering, unchanging champion. In almost every interview with a Sanders voter, they eventually utter some variation of the phrases: "I trust him" or "I believe him."

That bond with Sanders, rooted in the constancy of his ideas over many decades, is a striking contrast to the indecision and uncertainty one often hears from voters at the events of other 2020 candidates.

The connection to Sanders and his policies is personal, and once his supporters become believers, it has been hard, if not impossible, for the other campaigns to peel them away. His backers view the 2020 campaign as a reckoning for the Democratic Party, a time when the party must recognize its failure to lift disaffected working class voters.

When Clinton defeated Sanders in the Democratic primary four years ago, Uriel Guzman of Santa Ana voted for Green Party Nominee Jill Stein -- and he has no regrets about that vote, because he believes Trump's victory was a much needed wakeup call for Democrats.

"I feel like he's the only one who is actually speaking to us," said Guzman, a 23-year-old Latino who has struggled with rising college tuition and housing costs. "He understands our issues. He is speaking to our community -- I mean he's here in Santa Ana. That never happens. We're always overlooked."

Sanders understands, Guzman said, that if someone like him got really sick, his family wouldn't be able to help him: "We wouldn't have the money to really survive," he said in an interview with CNN in Santa Ana.

It's a point that was echoed by Garcia, of Anaheim, who said he trusts Sanders to push through Medicare for All without compromise.

"Every other country that's first world provides health care to its citizens and I think it's barbaric that the United States does not give health care to its people," Garcia said.

Multi-generational support

Sen. Bernie Sanders and his wife Jane Sanders arrive for a campaign rally at Vic Mathias Shores Park on February 23, 2020 in Austin, Texas.

The certitude of Sanders voters, both in the candidate's convictions and in their support for him, is perhaps the most overlooked aspect of his candidacy. And it is not just his most youthful supporters, who often get the most attention.

Over the past six months, his events have become increasingly multi-generational, with older voters often telling CNN they embraced his candidacy after hearing about it incessantly from their children. In Iowa early this year, one voter told the Vermont senator during a town hall in West Des Moines that she began paying more attention to him after her children came to her each week asking her to donate part of their allowance to his campaign.

Sanders' authenticity, compared with other candidates who have hedged and wavered on their positions while appearing to follow the trajectory of the polls, ultimately pushed Teresa Miller, a 43-year-old from Corona, into the Sanders camp last fall. It wasn't just Sanders himself; it was the strong feeling of connection she felt among his backers, the sense of a shared struggle.

Miller, who is Latina, said Massachusetts Sen. Elizabeth Warren was her top choice until she went to one of Warren's rallies.

"It was completely old white women. I felt completely out of place there and it made me wonder what she was doing to connect with Latinos and minorities," Miller said. "I tried to not let that bother me, but then she kind of walked back her Medicare for All plan."

Sanders' unyielding advocacy for universal health care ultimately won her over.

"There's no means testing with him," she said.

When Warren said in January that Sanders had told her in a private conversation that he didn't believe a woman could win the presidency, Miller was offended by what she saw as an attempt by Warren to paint Sanders as sexist.

"That's not Bernie. That's not his crowd," said Miller, an office supervisor for an architecture firm.

Other supporters note that many of Sanders' ideas -- once viewed as the product of the progressive fringe -- are now essentially part of the Democratic platform in 2020. They point out that his policy positions have often been the same since the 1970s.

"He's been doing and saying the same thing (since) when it wasn't popular and he had to come up against a lot of friction," said Karon Finn, 77 of Grimes, Iowa.

"He's got such a long record of being very steadfast (about) the things I care most about, which are education, health care and the middle and lower class in this country," said 57-year-old Elizabeth Duffy of Acworth, New Hampshire, who watched Sanders speak during an early February rally at Keene State. "He's always been clear and steadfast about what he talks about."

Allison Schwiegeraht, a 21-year-old student from UNC Greensboro who is studying environmental and sustainability studies, attributed Sanders' appeal to his passion on the climate crisis and environmental issues.

"He always really knows the right thing to say," Schwiegeraht said. "He's dedicated his whole life to this. Since he was also in his teenage (years) and in his early twenties, he just has a real passion for this -- and it's really hard to find that in a candidate, or really in any public figure."

'Not me. Us.'

Sen. Bernie Sanders greets supporters during a primary night event on February 11, 2020 in Manchester, New Hampshire.

The connection Sanders has, even with voters who have a very different life experiences than his own, is one that his campaign tried to build through all of 2019, and even before that when his team began encouraging their supporters to share stories of their economic struggles on social media.

The effort to build a stronger connection with voters than he did in 2016 came from Sanders himself and his wife Jane. It was a recognition from the candidate that in 2016, he often talked at voters rather than listening to them in speeches that could span as long as an hour and 45 minutes.

Sanders wanted to foster a sense of community, the foundation of a campaign slogan that became, "Not me. Us."

"They knew 2016 had been more academic, not as personal," Sanders senior campaign adviser Jeff Weaver said of the campaign shift. "They wanted to make what he was talking about connect -- to make it relevant to real people's lives."

Sanders became a better candidate, his advisers say, through those smaller, more intimate events -- where he asked voters for their stories about their economic troubles in the Trump economy.

"He understands what we go through and he doesn't fake it," said Destinee Campbell, a 19-year-old sophomore studying social work at Bennett College, a historically black college in North Carolina. She said she was confident Sanders would dedicate his presidency to improving the lives of minorities and women, even though that has been far afield from his own life experience.

"He actually seems like, if he hasn't been through it, he knows people who've been through it and understands what we need," said Campbell in an interview with CNN during Sanders' visit to the college last September. "He understands middle-class, real life situations. He understands us."