The Democratic establishment was shocked—and in some cases appalled—by Bernie Sanders’s insurgent bid for president last year. How could 12 million primary voters cast ballots not for market-friendly progressivism or New Deal liberalism, but democratic socialism? And against a Clinton, no less? But astonishment eventually gave way to acceptance, even implicitly from the nominee herself: the success of Sanders’s campaign was no fluke, proving that the Democratic Party had moved decisively to the left.

But 2016 was not the year the party became more progressive. It was merely when the establishment Democrats realized it had moved. Many observers recognized a shift underway years earlier. In 2013, in a New Republic article titled “Hillary’s Nightmare? A Democratic Party That Realizes Its Soul Lies With Elizabeth Warren,” Noam Scheiber accurately predicted the rift exposed by last year’s primary, arguing that it would “cut to the very core of the party” in the next race for the White House:

On one side is a majority of Democratic voters, who are angrier, more disaffected, and altogether more populist than they’ve been in years. They are more attuned to income inequality than before the Obama presidency and more supportive of Social Security and Medicare. They’ve grown fonder of regulation and more skeptical of big business.2 A recent Pew poll showed that voters under 30—who skew overwhelmingly Democratic—view socialism more favorably than capitalism. Above all, Democrats are increasingly hostile to Wall Street and believe the government should rein it in.

On the other side is a group of Democratic elites associated with the Clinton era who, though they may have moved somewhat leftward in response to the recession—happily supporting economic stimulus and generous unemployment benefits—still fundamentally believe the economy functions best with a large, powerful, highly complex financial sector. Many members of this group have either made or raised enormous amounts of cash on Wall Street.

Sanders won the support of the first, ascendant side of that divide. That would seem to to put the Vermont senator in a position to be the party’s new standard-bearer—especially given that, according to recent polling, he’s the most popular politician in the country. But he has returned to the Senate as an independent rather than a Democrat, aiming to “transform the Democratic Party” from the outside; what’s more, he’s 76 years old. This power vacuum has provided a clear opening for a new, progressive leader of the party—and she’s primed to occupy that role just as Scheiber foresaw, albeit a little later than he suggested. “We are not the gatecrashers of today’s Democratic Party,” Warren told Netroots Nation this year. “We are not a wing of today’s Democratic Party. We are the heart and soul of today’s Democratic Party.”

The 68-year-old Massachusetts senator is right—and she’s not the only one who says so. Amy Walter, the national editor for the Cook Political Report, wrote last week that “it’s going to be very difficult for a Democrat to win the nomination of his/her party on anything but the Warren platform.” Walter cited Pew Research data showing that “Democrats have moved dramatically leftward since the 1990s on issues like the social safety net, immigration, and race relations. On those issues, the so-called Warren wing represents the mainstream of Democratic opinion.” Congressman Jamie Raskin, vice chair of Congressional Progressive Caucus, told me Warren “does define the center of gravity within the Democratic Party.” Even the center-left Brookings Institution scholar Bill Galston, who disagrees with Warren on many policies, acknowledged her ascendancy in this moment. “If you forced me to lay down a bet today on the most likely nominee of the Democratic Party, it would be Senator Warren,” he said—while emphasizing that this was “a simple assessment of current realities,” not a prediction. “If you asked me to define the center of gravity, it would be pretty close to where she is right now.”

This reality has major implications for the future of the party—in next year’s 2018 midterms, the 2020 presidential election, and beyond. If Warren is now the soul of the Democratic Party, what will this transformed party look like and what will it fight for?

It’s hard to overstate Sanders’s role in shaping the American left today. Raskin rightly noted that Sanders “is in the center of progressive politics.” “It’s his bill that’s defining the Democratic agenda on healthcare, not Elizabeth Warren’s,” Walter told me. “There’s no doubt that on certain issues he’s the one setting the agenda.” But Warren, unlike Sanders, is a loyal partisan who represents a consensus between her party’s left-wing economic populists and groups aligned with the establishment like the Center for American Progress, where she keynoted an Ideas Conference earlier this year. The establishment feels more comfortable with Warren’s mission of reforming and “unrigging” existing economic and political systems, compared to Sanders’s approach of indicting and supplanting these systems altogether. “Warren is a party person,” Howard Dean, the former Vermont governor and ex-chair of the Democratic National Committee, told me. “Bernie is an iconoclast.”

From a historical perspective, Warren’s politics are firmly rooted in an American tradition. Raskin describes them as “kind of a return to the progressivism of the early 20th century.” He sees Sanders’s ideology as closer to “European-style social democracy,” observing that the Vermont senator started off his campaign last year with “kind of an old-school Marxian approach with the class struggle explaining everything.” Galston said Sanders has “a very statist agenda,” and he sees Warren as “more of what I’d call a Naderite reformer,” in the mold of consumer protection crusader Ralph Nader.

Warren, a former Harvard professor who had conceived and set up the Consumer Financial Protection Bureau under the Obama administration, rose to prominence by effectively positioning herself as a champion of working families and the middle class. “That was not an idea that came out of Clinton-esque triangulation,” Raskin said of the CFPB. “That’s both a great victory for her but also a demonstration of how ideas can change and shift the notion of what the political center is.”

“We are living in an economic populist moment,” said Adam Green, co-founder of the Warren-aligned Progressive Change Campaign Committee, “and Elizabeth Warren is very much the north star of the Democratic Party in this moment, providing direction for where the party can go to get out of the darkness.” He described her as a “unique figure who has gotten both more popular with her base and more credible with the political establishment” over the years, channeling the public’s economic frustration and picking strategic battles she won with a specific set of political skills.

“I would say she’s the best progressive Democratic politician I’ve seen since Bobby Kennedy,” said Bob Kuttner, the co-founder and co-editor of The American Prospect, lauding her for “making pocketbook populism feel mainstream.” Kuttner added, “She managed to block Barack Obama from appointing Larry Summers to chair the Fed. She’ll go to heaven for that by itself.” Warren became famous for viral confrontations with bank regulators and the likes of Obama Treasury Secretary Timothy Geithner, but Kuttner said she’s also “a great inside player” on Capitol Hill.

“She’s been very intentional about building coalitions across the Democratic Party—and occasionally with Republican senators—for her economic populist position,” Green said, “and has made it increasingly safe for Democratic politicians to follow her lead.” To demonstrate how Warren “proves the credibility of her ideas,” he pointed to Senator Jon Tester of Montana. “People like Jon Tester, who is a prairie populist but not seen as a left-wing ideologue, felt safe not just following her into battle but taking a leadership role” in opposing Summers.

Moderate Democrats won’t all agree that Warren has become the center of the party. But Warren elicits respect from unusual sources, including the man Bloomberg Businessweek once called “Wall Street’s Favorite Democrat”: Congressman Jim Himes, chair of the centrist New Democrat Coalition. Asked about Warren’s presidential prospects—and Walter’s contention that “the Warren platform” could end up as a litmus test for 2020—he said, “I think it’s possible. There’s a lot of energy on the left wing of the Democratic Party.” Though he hails from a district with “a huge amount of financial services,” the congressman offers plenty of praise for one of Wall Street’s harshest critics. “I’ve never sort of tallied it, but I agree with Elizabeth Warren on much of what she says,” he said. “I agree with a lot of what she puts out there.” He added, “The press desperately wants to foment or preserve the notion that there’s this massive split between the Bernie Sanders and Elizabeth Warren gang and the Clinton gang—between the progressives and the moderates—and it’s just not true.

Himes is quick to draw distinctions between Warren, who is “fundamentally a free markets person,” and Sanders, a democratic socialist. “In as much as we both respect the power of markets in a way that Bernie Sanders may not, I think she’s more mainstream,” he said. “I think she has a perfectly supportable thesis, which is that markets work well when they’re well regulated and generate bad outcomes when they’re not. That’s a perfectly acceptable premise to me. You know, I see her using the word ‘free’ a lot less than I see Bernie Sanders using the word ‘free.’ It may just be that she acknowledges that nothing is free. It’s simply a question of who pays for what.” Himes also sees a difference between how the two senators talk about the “rigged” economy, such as Warren’s reference to “tricks and traps.” “When you talk about ‘tricks and traps,’” he said, “you’re not saying the system is fundamentally corrupt or evil, you’re saying it can be corrupted.”

That’s why Himes sees an “establishmentarian distinction” between them. “She might take offense at this,” he said of Warren, “but I don’t regard her as a non-establishment figure in the way I regard Sanders as a non-establishment figure.”

Josh Barro thinks Warrenism is just what Democrats need. “I think there is a convincing way forward for the party,” the Business Insider senior editor wrote in June. “Roughly, it involves being less like Hillary Clinton and less like Bernie Sanders, and instead being more like Elizabeth Warren.” The party, he added, “should make a list of corporate practices that grind people’s gears and ask whether there’s a compelling economic rationale for them.... And they should explain how doing so will make it easier for people to buy the things they need to live the way they want, with their own earnings. This approach isn’t neoliberal, and it isn’t socialist, either. It’s about treating markets as a means to an end and using the government to ensure those markets serve the interests of regular people. And it doesn’t have to involve growing the government or asking people to trust it with more of their money.”

Jim Kessler, vice president of the centrist Democratic think tank Third Way, opposes this approach—and the idea that Warren represents the new party mainstream. “She represents a wing of the party, and she represents it well,” he told me. The Democrat he thinks best represents the party consensus is the one who’s been preaching bipartisanship and moderation in recent weeks: former Vice President Joe Biden. But Kessler may end up in the minority. Walter told me “there is still a deep love and appreciation for Joe Biden, but his policies, especially if he runs basically where he’s been in the past and where he was with the Obama administration—I don’t know that it would be as popular as where Warren is coming from.”

That’s why her politics are intriguing to Democrats of many stripes. “The contest between Sanders and Clinton reflected progressive populism and liberal feminism,” Raskin said. “Elizabeth Warren is someone who merges them both. You could view her as the synthesis of the divides in the party we had in the 2016 election—a candidate who would leave nothing out and leave nobody behind.” Polling shows her agenda, which overlaps significantly with Sanders’s, isn’t just popular with Democrats. Most voters supported a $15-an-hour minimum wage, according to Pew survey last year. “Broad, bipartisan majorities support debt-free higher education,” a Demos poll found last October. The notion that the system is rigged in favor of big corporations certainly isn’t out of step with public opinion. Like all progressives, Warren has work to do selling single-payer healthcare, which doesn’t yet have clear majority support. But enthusiasm for Medicare for All is growing among Democrats in Washington and across the country.

Himes has reservations about Warren’s broader appeal. “How would Elizabeth Warren play in Ohio?” he mused on Tuesday. “It’s a huge question, and I’m not sure I have a preconceived notion. On the one hand, I think she has an authenticity and a clear passion that is going to be appealing to a lot of people. How she would manage gun issues that are pretty important in rural Wisconsin, other social and cultural issues, I think is an interesting question.” The question is whether Democrats should even be tailoring their message for places like rural Wisconsin, versus trying to energize a diverse swath of voters across the country. Raskin is fond of saying he has no ambition to be in the political center; he aims to occupy the moral center, and bring the politics to him. That’s a safer stance for a liberal congressman than a presidential candidate, and centrists rightly observe that public opinion hasn’t caught up to a whole host of progressive priorities. But as Kuttner said, mainstreaming “pocketbook populism” is Warren’s great gift, and it’s notable that even moderates like Himes—an ally of Wall Street and leader of an overtly moderate congressional caucus—won’t count her out. “If she can make the leap to being a candidate that played in the rural midwest,” he told me, “it could be really interesting to watch.”