After decisive victories in the Alaska, Hawaii, and Washington Democratic primaries, the fate of Bernie Sanders’s campaign for President is still unclear. Photograph by Matt Mills McKnight / Getty

“Don’t let anyone tell you we can’t win the nomination, or win the general election,” Bernie Sanders told a huge crowd in Madison, Wisconsin, on Saturday evening. “We’re going to do both of those things.” The Vermont senator’s optimism was understandable, as was the enthusiasm of his supporters, who repeatedly interrupted him with chants of “Bernie! Bernie! Bernie!,” and “We believe that we can win!”

On a day the networks dubbed “Western Saturday,” Sanders won big victories in three caucus states: Alaska, Hawaii, and Washington. In all three of these contests, he picked up more than seventy per cent of the vote. The outcome in Washington, where more than a hundred delegates were at stake, was particularly striking. From urban King County, which includes Seattle, to Asotin County, in the remote southeast of the state, Sanders came out ahead. The Seattle Times described the result as a landslide.

Since being swept on March 15th, when Clinton won five states, including Florida and Illinois, Sanders has won five of six contests, all of them caucuses in the West. (Last Tuesday, he got more than two-thirds of the vote in Idaho and Utah. Clinton won the primary in Arizona.) During his speech on Saturday, Sanders said that his campaign had known it would struggle in the Deep South, describing it as “one of the most conservative parts of the country.” Then he added, “But we knew things would improve as we headed West.”

Sanders’s resurgence raises two important questions: Does he have a realistic chance of defying the punditry and snatching the nomination? And, even if he doesn’t ultimately win, how will Clinton and the Democratic Party deal with him and his supporters?

Despite what happened on Saturday, the delegate math and the betting odds still favor Clinton. In the past week, Sanders picked up a hundred and twenty-eight delegates and Clinton picked up seventy-six, a net gain for Sanders of fifty-two delegates. But the lopsided results on March 15th and the earlier contests in the South left Sanders a long way behind. Even after his gains on Saturday, he trails Clinton by two hundred and sixty-eight delegates—and that doesn’t count Clinton’s huge advantage in superdelegates.

The good news for Sanders is that eighteen states have yet to vote, plus the District of Columbia, Guam, Puerto Rico, and the U.S. Virgin Islands. In total, two thousand and seventy-three delegates are still available. After Saturday, Sanders needs to obtain about fifty-seven per cent of them to achieve a majority of elected delegates. If he did that, he would obviously be in a strong position going into the convention, in Philadelphia, which might in turn help his campaign persuade some of the superdelegates to switch sides.

But the challenges facing Sanders are enormous. Michigan apart, most of his key victories have come in caucuses, which put a premium on organization and voter enthusiasm. Sanders has plenty of both. Setting aside the offshore territories, however, the only caucus states left are North Dakota and Wyoming. All the rest of the contests are primaries, in which Clinton has performed much better.

The next vote is scheduled for Tuesday, April 5th, in Wisconsin, where Sanders has a decent chance of coming out ahead. The polls are close, he’s been drawing big crowds, eighty-eight per cent of the population is white, and Wisconsin has a strong radical tradition. On the other hand, the Clinton campaign has also targeted the state, and it has the support of many labor unions, which have been battling Governor Scott Walker for years. Even if Sanders does prevail, the result is likely to be close, which means the ninety-six delegates will probably be split fairly evenly. Clinton’s lead is likely to remain largely intact.

After Wisconsin, the race will move east to some big and diverse states, where the former Secretary of State’s support among minorities will be an important factor. On April 19th, the New York primary will be held. A week later, five more states along the Northeast Corridor will vote: Connecticut, Delaware, Maryland, Pennsylvania, and Rhode Island. More than seven hundred and fifty delegates will be up for grabs in these six contests. Early polls aren’t necessarily reliable, but many of the ones that have been conducted in these states show Clinton with big leads. In New York, for example, a poll released by Siena College earlier this month showed her leading Sanders by twenty-one percentage points.

To win the nomination, Sanders needs to record some big upsets in the Northeast, then rack up victories by large margins in Western states like Oregon, Wyoming, and California, whose primary isn’t until June 7th. After Saturday’s results, the second part of that scenario doesn’t seem wholly outlandish. In his speech afterward, Sanders pointed to a recent poll by Bloomberg that showed him running slightly ahead of Clinton nationwide. And, according to the Huffington Post’s poll of polls, he is within striking distance in California.

These are encouraging numbers for Sanders supporters, but he still has to demonstrate the ability to win states where the demographics and polls favor Clinton. Apart from Michigan, he hasn’t yet managed this, and that explains why, in the betting markets, Clinton is still the heavy favorite to win the nomination. At the online site Betfair, you would have to wager a hundred dollars on Clinton to win ten dollars if she prevails. According to Predictwise, a Web site that aggregates information from betting markets and opinion polls, the probability of Clinton getting the nomination is ninety-two per cent, and the probability of Sanders winning is just eight per cent. Perhaps significantly, that figure hardly changed after Saturday’s results.

Sanders and his supporters point out, with quite a bit of justification, that the pundits and the betting markets have underestimated him all along. Before Saturday, who would have predicted that Sanders would best Clinton by sixty-four percentage points in Alaska, forty-six points in Washington, and forty points in Hawaii?

The Sanders campaign is an impressive phenomenon, and in states like New York and California it is still growing. While out shopping on Third Avenue in Brooklyn yesterday, I came across hundreds of Sanders supporters, almost all of them young, who had gathered to mark the opening of a local campaign office. The candidate was thousands of miles away, in Wisconsin, and the results from the Western states were still hours away, but a large crowd of his followers had given up its Saturday morning to express support for him.

“Hillary Clinton and I agree that it is imperative that no Republican make it to the Oval Office,” Sanders said in Madison. Where the two candidates didn’t agree, he went on, was regarding who was best positioned to stop the Republicans. “One of our campaigns has created an enormous amount of enthusiasm and energy that will lead to a large voter turnout in November,” Sanders added. “That campaign is our campaign.”

At this stage, even the most loyal Clinton supporter would have difficulty disputing that claim, which has implications for both the general election and the remaining primaries. The young voters and progressive voters who have flocked to Sanders are key components of the Obama coalition. If Clinton does get the nomination, she will desperately need their backing. And she will also need to tap into some of the enthusiasm and commitment that the Sanders campaign has engendered.

Should Donald Trump become the Republican candidate, it would certainly help unite the Democrats. But, going into a general election, Clinton would also want to obtain the vigorous endorsement of Sanders. And that means her campaign, even as it tries to defeat the Vermont senator over the coming weeks, also needs to avoid alienating him.

This post was updated to correct the percentage of delegates Sanders needs to win from here on to achieve a majority of elected delegates.