Bernie Sanders’ path to the White House has been incredibly narrow but, after his near-draw in Iowa on Monday night, there’s clearly open road ahead of him.

On Tuesday, the race in which pundits long-ago declared Hillary Clinton the presumptive victor will begin in earnest; sit tight, it’s going to be a very long, bumpy ride.

The margin between Sanders and Clinton was razor thin all of Monday night – certainly thinner than anyone would have imagined possible last spring, when he was down by 42 points in a national poll. Coming in anywhere close to Clinton in the Iowa caucus would’ve been a significant victory for Sanders; the near-tie showed the deep resonance of his message.

The actual results underscored what he and his supporters have said all along: establishment Democrats have underestimated him and the power of his movement.

The chief argument against Sanders for his entire campaign is that he’s unelectable in a national election and, by extension, ineffective as a candidate or a statesman. He’s alternately been written off as a fringe candidate, an adorable elderly relative and more subtly, as a political tool for pushing Clinton the left.

But Monday night proved that he could win and, in proving it, he’s weakened Clinton by exposing her as something other than the inevitable candidate we had all but assumed her to be. Some Sanders staffers have argued Sanders definitely did win if you count raw totals and not state delegates; given the geographical layout of Iowa, that claim is likely if unproven. (More than a quarter of Sanders’ supporters come from just three counties – which awards only 12% of delegates; the caucus structure is thought to favor Clinton significantly).

Numbers aside, by sheer momentum Iowa was a win for Sanders – and that’s how progressive groups were framing it before the race was called. Democracy for America’s Charles Chamberlain – which had endorsed Sanders weeks ago – was calling the night’s results are “a huge win for Bernie” and “a major upset” for Clinton before Sanders even took the stage.

“Together, the people of Iowa and millions of grassroots progressives all across the country, turned a candidate who was polling in the single digits just six months ago into a race-altering force of nature in the Democratic primary and national conversation,” he said in a statement.

Sanders, though, took a more cautious approach to the results, holding off on commenting late into the night as the numbers continued to roll in.

When Sanders finally spoke on Monday night, he drove home the message behind their virtual tie. “What Iowa has begun tonight is a political revolution,” he said, as the crowd erupted in screams. “When young people and working people and seniors begin to stand up and say loudly and clearly enough is enough ... that the government of our great country belongs to all of us and not just billionaires, when that happens, we will transform this country.”

It was textbook Bernie: inspirational, focused on class inequality and mad as hell. And every time he got fired up about a moral point – like his assertion that healthcare is a right not a privilege – the crowd returned his fire with shouts and calls of “Bernie!

“You guys ready for a radical idea?” Sanders asked his ecstatic audience tonight. “Well, so is America.”

Sanders rode his self-proclaimed radical ideals all the way to a virtual tie in Iowa which, as Jamelle Bouie noted at Slate, marks the first time in a century that a socialist has managed to build a movement with real mass appeal, not to mention an actual shot at the presidency. Whatever shape the Democratic Party takes in the coming years, it will owe something to that phenomenon – which is to say, to Sanders, and not just because of how he influences Clinton.

If Sanders had lost definitively in Iowa (as almost everyone once predicted) his campaign would effectively be over before New Hampshire voters hit the booths next week. Well he didn’t and it’s not – and Clinton’s staff had better get to shoring up that vaunted Southern firewall before South Carolinians feel the Bern, too.