As the Nevada caucus votes that would give Bernie Sanders a sweeping victory, and newfound momentum for his antiestablishment bid for the Democratic presidential nomination, were beginning to be counted, the rival campaign of Michael Bloomberg growled out another objection to the anticipated results of a contest in which the billionaire candidate had chosen not to participate.

“The Nevada results reinforce the reality that this fragmented field is putting Bernie Sanders on pace to amass an insurmountable delegate lead,” complained Bloomberg campaign manager Kevin Sheekey. “This is a candidate who just declared war on the so-called ‘Democratic Establishment.’ We are going to need Independents AND Republicans to defeat Trump—attacking your own party is no way to get started. As Mike says, if we choose a candidate who appeals to a small base—like Senator Sanders—it will be a fatal error.”

Sheekey would have been wise to wait for the full picture of what the Sanders campaign accomplished in the battleground state where the senator and his backers put a heavy emphasis on grassroots organizing and mobilization.

The tabulation of Saturday’s caucus votes and polls of caucus-goers refuted the false premise of Bloomberg’s campaign that Sanders has a narrow appeal. The senator clinched a “huge win,” in CNN’s words. That win, coming on the heels of popular-vote victories in Iowa and New Hampshire, positions Sanders to counter the naysayers who keep questioning whether the democratic socialist is electable. That’s a rare opening for any candidate—and one that he now must seize by making a savvy argument for why he can not just win the Democratic nomination but also defeat President Trump in November.

In Nevada, Sanders showed genuine signs of strength. The senator swept the first round of caucus voting, securing a 2-1 margin over his closest rival and the erstwhile front-runner, former vice president Joe Biden. Sanders substantially increased his lead in the second round, where backers of contenders who fell short of viability realigned with a unity candidate.

By Sunday morning, with a majority of the precincts reporting, Sanders was winning 46 percent of county delegates from across the state and looked to be on track to secure as many as 10 pledged delegates to next summer’s Democratic National Convention. The closest contender, Biden, was picking up almost 20 percent of county delegates. Former South Bend, Indiana, mayor Pete Buttigieg, was at 15 percent. Three other candidates—Massachusetts Senator Elizabeth Warren, Minnesota Senator Amy Klobuchar, and billionaire Tom Steyer—finished with 10 percent or less.

Entrance polls of Nevada caucus-goers showed Sanders winning among men and women, running a solid second (behind Biden) in the race for the African American vote, carrying the Latino vote with 51 percent of the total, grabbing 65 percent of the vote of Nevadans under age 29 and 50 percent of those aged 29 to 44. Sanders swept the union vote in a state where a key labor organization had raised concerns about his support for single-payer Medicare for All health care reform. He finished up with a 2-1 advantage over the next-strongest candidate, Warren, among the 64 percent of voters that identified as liberal. And he tied Biden among the 34 percent who identified as moderate or conservative.

Sanders now finds himself in a complex position. He is the front-runner in the Democratic race. Yet his is still a dissenting and challenging voice within the party. On the eve of the caucuses, the senator declared, “I’ve got news for the Republican establishment. I’ve got news for the Democratic establishment. They can’t stop us.”

That line set off Bloomberg, party insiders, and a lot of pundits, who ripped into Sanders and his antiestablishment campaign. What Bloomberg and his apologists fail to understand is that challenging political power brokers has significant appeal among grassroots Democrats and independents. Notably, in Nevada, of the 17 percent of caucus-goers who identified as independents, Sanders won 50 percent. The next-closest contender, Buttigieg, was at 13 percent, and no one else was in double digits.

With his front-runner status confirmed after the first three contests of 2020, Sanders needs to engage with the electability debate in a more serious way. He really does have to make the “Bernie Beats Trump” message of his campaign posters central to his message going forward. Democrats know where he stands on the issues, and they agree with him—62 percent of those polled in Nevada said they favor responding to health care concerns with “a government plan for all instead of private insurance.” But Democrats and independents who lean toward the party are desperately determined to defeat Trump; in Nevada, two-thirds of those surveyed said it was more important to have a candidate who can upend the president than a candidate they agree with on issues.

For Sanders, the next opportunity will come in Tuesday’s debate in South Carolina, for which he, Bloomberg, Biden, Warren, Buttigieg, Klobuchar, and Steyer have qualified. There’s pressure on several of them to drop out, but none are likely to do so before Saturday’s primary in South Carolina, where Biden still leads in most polls but Sanders and Steyer have surged.

In fact, Nevada gave several candidates room to move. That’s certainly true of Biden, who announced, “We’re alive and we’re coming back and we’re gonna win. I think we’re in a position now to move on in a way that we haven’t been until this moment. I think…we’re going to win in South Carolina, and then Super Tuesday and we are on our way.”

Elizabeth Warren, who got points for a strong showing in last week’s debate, is also positioned to go forward. Her fourth-place finish in Nevada was not what she’d hoped for, but she can make a credible argument that a substantial portion of the caucus votes were cast early—before her thrashing of Bloomberg in the debate caused a number of Democrats to take another look at her campaign.

The Progressive Change Campaign Committee’s Maria Langholz observed Saturday night, “The top priority for all candidates is momentum going into Super Tuesday. Nevada clearly shows that Warren got a huge boost between early votes cast before the debate and day of voting after the debate—in some places as much as a 20 or 25 point boost.” Warren, who announced she’d raised $14 million in the 10 days before the Nevada caucuses, needs another strong debate showing and a better-than-expected finish in South Carolina. But she and Buttigieg can argue with Biden that their lanes remain open.

Ultimately, however, it is Sanders who will be speaking from a position of strength. As a candidate who quit the competition, Andrew Yang, said Saturday, “It looks like Bernie’s going to win Nevada by a more significant margin than was the case in Iowa or New Hampshire. He is gaining steam. If he wins South Carolina it will be hard for another campaign to make a case with Super Tuesday only three days later.”