Bernie Sanders may have won Vermont, Utah, Colorado, about half the Texas delegates and a plurality of California, but his path to the Democratic nomination has narrowed.

The senator’s supporters — just like those of Sen. Elizabeth Warren — are understandably distraught. But a loss of the nomination doesn’t have to mean the loss of a movement.

To understand why, let’s go back 16 years. Back to Drexler’s Bar-B-Que, that bygone Third Ward institution just off of Dowling Street bearing the name of retired NBA great “Clyde the Glide” Drexler. Back to a campaign stop that U.S. Rep. Dennis Kucinich made there in his bid for the Democratic presidential nomination.

It was December 2003. I was a graduate student at the University of Houston and an activist. I attended Kucinich’s meetup out of curiosity. I recall a packed room of supporters greeting the elfin liberal.

Kucinich never had a chance at the nomination. Winning wasn’t the point. The man was a vegan. Back then, that label was troubling to most Americans, if not sacrilegious to most Texans — and perhaps even more of a deterrent than “democratic socialism” is today.

That didn’t keep him out of Drexler’s though. His team saw to it that cooks at that bastion of mesquite-smoked meat prepared a special vegan breakfast for the occasion.

Kucinich didn’t win a single state but he stayed in the race. His candidacy wasn’t about the man; it was about a movement. His supporters aimed to transform the Democratic Party from within by getting delegates to the state conventions and changing party platforms from the ground up.

Kucinich had a terrible record in Congress in terms of passing legislation. Of the five enacted bills for which he was primary sponsor during his time in Congress from 1997 to 2012, two were to rename post offices. But he voted consistently according to his principles, including against the invasion of Iraq. That should sound familiar if you’ve looked into Sanders’ record.

Four years earlier, in 2000, the Green Party had garnered less than 3 percent of the popular vote in the general election. Not enough to establish a viable third party but enough to have tipped the balance to George W. Bush in battleground states. Four years later, with progressives wringing their hands much as they are now, Kucinich supporters helped inject new thinking into the Democratic Party rather than challenge the two-party system.

“The idea was to introduce resolutions for issues like health care that would benefit everybody,” says Theresa Keefe, a longtime Houstonian who volunteered for the Kucinich campaign and whose husband, Keith Koski, went to the Democratic state convention as a delegate.

Was the activism that coalesced around Kucinich of any consequence? It’s hard to know. Party platforms are largely aspirational. What’s clear is that ideas considered radical then — decriminalization of marijuana, equal rights for LGBT people, focusing on crime prevention instead of incarceration — have gone mainstream.

The lesson for disappointed Sanders and Warren supporters? If it’s really about the ideas, don’t give up on them. The huge turnout for progressive candidates in 2020 dwarfs what happened in 2004. If the rag-tag Kucinich movement had an impact over a decade-long period, today’s progressives are moving the needle much faster.

As Super Tuesday results rolled in, U.S. Rep. Dan Crenshaw called for “conservatives to own the climate change issue” in the National Review, noting that Republicans should not simply reject what he calls “extreme solutions” but come up with their own. As flawed as his New Energy Frontier proposal is, Sanders and Warren supporters should take pride in the fact that industry and politicians have had to answer for climate change and in some cases, take real action.

If Joe Biden wins the nomination, he will have to address student loans, inequality, climate and the other core issues to win over the progressive wing. And he must do so with urgency. He can’t just expect them to fall in line out of a shared desire to defeat President Donald Trump.

Assuming Sanders does not win the nomination — and he still could — his supporters should continue organizing, while understanding that your ideas have to be persuasive to those who think differently. And change requires compromise.

“Whether Sanders is nominated or not, his supporters are doing a tremendous service by raising issues,” says Bill Crosier, a retired engineer who served as the southeast Texas coordinator for the 2004 Kucinich campaign.

“Don’t give up the fight,” adds Koski. “The strength of your coalition shows the issues you are promoting are not going away and the future holds surprises.”

Drexler’s closed long ago but Houston’s barbecue options still abound, including Green Seed Vegan. Dowling Street is now called Emancipation Avenue. A bipartisan coalition in the Texas Legislature led the nation in criminal justice reforms. Diversion programs have become commonplace for low-level pot offenses. Even so, progressives have plenty of reasons to be disillusioned.

To keep the change coming, progressives must put the movement before the man, and the woman.

Mankad is the Chronicle’s Op-Ed editor and a member of the Editorial Board.