It started with Elizabeth Warren, but it certainly won’t end there. The waterfall of Democratic candidates looking to challenge Trump is unfurling, and there’s no telling how many there will be. Many perceive Trump to be a weak opponent, and with no clear front-runner in the party, it seems as good a time as any to run for the most powerful job in the free world.

Many pundits have strong opinions about whether 2016 Democratic candidate Bernie Sanders should run again, especially alongside the candidates that have already entered the ring. But here’s the thing: He’s already won.

In 2016, a zealous old man came onto the scene with negligible name recognition and fought against one of the largest political machines in U.S. history. The man didn’t even comb his hair for it. Instead of big donor parties, he used social media to host large, free rallies. He wanted Medicare—for all. He refused super PAC money. He did absolutely everything a politician should not do.

And then, against all odds, he electrified millions and nearly won the nomination anyway.

2020 may only be four years later, but look how far we’ve come. Alexandria Ocasio-Cortez—who sharpened her teeth as an organizer for Sanders’ campaign—upset the establishment and became the youngest woman in Congress. She’s already introducing legislation for a Green New Deal, she campaigned on Medicare for all, and she, too, refused money from political action committees. She has carried on Sanders’ tradition of not just dreaming, but of questioning why dreams can’t become our reality.

Democratic star and likely presidential candidate Beto O’Rourke also refused money from super PACs. Recently announced candidates Julián Castro and Tulsi Gabbard claim they won’t accept money from political action committees, and both have endorsed Medicare for all.

Sanders paved the way for progressives across the country.

The out-of-the-box pipe dream that “crazy old Bernie” ran on — with an ill-fitting suit and a nondenominational prayer — is the very platform that nearly every 2020 Democratic candidate so far seems to be adhering to.

It’s impossible to know if Sanders would have won a general election against Trump, but if he wasn’t the perfect antithesis to beat him, then why does the current slate of 2020 opponents seem to resemble him so closely? I understand—and love—that when they look in the mirror they don’t see an aged white man, but what they do see in that mirror is his platform. His enthusiasm. His disregard for the establishment. His penchant for change. Much like Hillary Clinton punched deep cracks in the glass ceiling for women (and we may see the result of that in 2020 too), Sanders paved the way for bold progressives across the country.

Sanders may not have won the nomination, but he moved one of the nation’s most stubborn political parties not just 10 or 20 percent toward him, but nearly entirely onto his platform. He took his campaign straight to the people and completely redefined the way campaigns are run. Just four years ago, he was seen as ridiculous for not taking big money from corporations; politicians had convinced us for decades that it would be impossible to run without them. But just four years later, we scoff at those who take money from big business connections.

If anything, Sanders is proof that an increasingly large part of being a successful politician is the ability to affect the public mindset. He may not pass these policies himself, but whoever does will do it along the path he helped create for them. It’s a whole lot easier to change the law when millions of Americans are on your side.

He awakened the dreams of the enthusiastic young — a powerful group with many votes left to cast

The Democratic primaries will only grow more complicated from here, and whether Sanders running again hurts or helps the party is something nearly every Twitter user has a hot take on. But the weight of the Bernie Sanders 2016 campaign is already felt in preparations for 2020—and will be felt in the years to come. Sanders awakened the dreams of enthusiastic young people—a powerful group with many votes left to cast. Bad health care and corporation-owned elections are no longer the inevitability they once were, and that’s a testament to how powerfully, and quickly, Sanders changed the national conversation. When history reflects back on this volatile political time, he may end up being the single most influential candidate to lose a party’s nomination in U.S. history.