Reporters who cover primaries, especially in off-years like 2018, often find themselves in a quandary. They’re expected to find meaning in each election’s results. But not many people vote in these primaries, and local issues are often more important than national ones. The resulting journalistic pronouncements are often built on sand, vulnerable to being washed away by the next wave.

After the May 15 primaries in Pennsylvania, Nebraska, Oregon, and Idaho, The Washington Post’s James Hohmann wrote that “Tuesday was a terrible, horrible, no good, very bad day for Democratic moderates.”

That was largely true. In a Nebraska congressional primary, left-wing candidate Kara Eastman won an upset victory over the establishment-backed Democrat, former Rep. Brad Ashford. Progressives also defeated establishment-backed candidates in Idaho and Oregon.

In Pennsylvania, leftist John Fetterman, with Bernie Sanders’s backing, defeated an establishment candidate in the contest for the Democratic nomination for lieutenant governor. And candidates backed by the Democratic Socialists of America scored impressive wins in three other Pennsylvania state races.

“The success of very liberal candidates in primaries across four states is causing a new bout of heartburn among party strategists in Washington,” Hohmann wrote, “who worry about unelectable activists thwarting their drive for the House majority.”

The heartburn was undoubtedly real. But the worry Hohmann describes is based on the proposition that “party strategists in Washington” know what makes candidates electable, a notion that is not supported by the Democrats’ electoral performance over the last decade.

The Nation’s John Nichols took a considerably more celebratory approach to the May 15 results, reveling in the Democratic primary victories of Pennsylvania’s openly socialist candidates. Under the headline, “Socialism Is on a Winning Streak,” Nichols quotes one candidate as saying, “We’re turning the state the right shade of red tonight.”

Yet what a difference a week makes.

“It was a pretty good night for the Democratic establishment,” Politico wrote of the May 22 primaries in Texas, Georgia, Kentucky, and Arkansas. “In four of the most crucial Houses races with primaries on Tuesday,” wrote Slate’s Josh Voorhees, “Democratic voters selected the DCCC’s preferred candidates.”

That conclusion was largely based on the suburban Houston primary contest between Lizzie Fletcher and Laura Moser. The Democratic Congressional Campaign Committee intervened crudely against Moser in late February, publishing an opposition memo on its website. The move inadvertently raised Moser’s profile in a multicandidate field, galvanized progressive groups to support her, and likely helped vault her into the runoff. Fletcher, a corporate attorney, won resoundingly in the May 22 runoff, with 67.1 percent of the vote. That sounds impressive, but a total of only 17,023 votes were cast in the Fletcher–Moser race, and Fletcher won by a margin of fewer than 6,000 votes.

It takes a certain selectivity to broadly interpret the May 15 results as an unadulterated victory for the Democratic establishment. Amy McGrath, the relatively mainstream Democrat who won a Kentucky congressional primary, took down the party’s first choice in the race. Stacey Abrams, who won the Georgia gubernatorial race, ran as a progressive. Abrams also embraced the progressive notion that Democrats are more likely to win by turning out their base than they are by reaching “persuadable” Republicans.

The experts’ crystal balls were clouded even further by June 6’s primary results. The Washington Post post-primary roundup was headlined “The Democratic Establishment Strikes Back in California, New Jersey and Other Primaries,” while The Intercept went with “Progressive Candidates Had a Very Good Night Tuesday.”

Establishment-backed Democrats did well in New Jersey’s congressional primaries, fueling another round of “leftists on the run” commentary in the mainstream media. At the local level, progressive challengers lost in three California district attorney races.

But The Intercept may have been closer to the mark than other outlets. Progressive Katie Porter defeated establishment-backed Democrat Dave Min in a California congressional primary, with the help of Sen. Elizabeth Warren and left groups like Democracy for America and the Progressive Congressional Change Committee. (EMILY’S List, which supports both progressive and establishment-oriented pro-choice women, also backed Porter.)

Progressive Ammar Campa-Najjar won in California’s 5th District. Left candidate Deb Haaland defeated two less progressive Democrats in New Mexico, and is now poised to become the first Native American woman in Congress. In a New Mexico legislative race, left candidates defeated three establishment Democrats in the state legislature, with help from the Working Families Party.

Punditry aside, none of these primaries provide enough information for solid predictions. There are, however, lessons to be drawn from the not-inconsiderable left-wing victories of May and June. The first is this: the fact that any candidate associated with the word “socialist” can win a major party’s primary suggests that a significant shift may be underway in American politics.

Media narratives, the flow of campaign contributions, and the actions of party leaders have all reinforced the idea that genuinely left-wing candidates are unelectable and must be shunned—if not for ideological reasons, then for pragmatic ones. That has changed now, and the de facto taboo on Democratic leftists has been broken.

This is especially true in Pennsylvania, where Summer Lee, Sara Innamorato, and Elizabeth Fiedler won their May primaries for the State House with the backing of the Democratic Socialists of America. Lee and Innamorato prevailed against the Costa cousins, two scions of a powerful Democratic family in Pittsburgh. Another DSA-backed candidate, Lee Carter, was elected to the Virginia House of Delegates in 2017.

What is Bernie Sanders’s role in this shift? “The revolution is real,” wrote The Washington Post’s David Weigel and Michael Scherer on May 16, “but it’s not clear Bernie is going to lead it.”

Weigel and Scherer noted that 10 of 21 candidates backed by Bernie Sanders have won during this election cycle, along with 46 of the 111 backed by the Sanders-affiliated group Our Revolution. What they don’t say is that this is an extraordinarily good run for candidates who are opposing a highly funded and well-organized political machine and whose political views were considered outside the mainstream as recently as two years ago.

Can left candidates keep winning Democratic primaries? If recent millennial polling is any indicator, the long-term outlook is promising. According to a recent survey by the University of Chicago’s GenForward project, 61 percent of millennial Democrats “express favorable views toward socialism.” Bernie Sanders carries significantly more influence than Nancy Pelosi with both Democratic and independent millennials.

These findings are consistent with a Harvard-Harris poll published earlier this year, which found that a majority of Democrats of all ages support “movements within the Democratic Party to take it even further to the left and oppose the current Democratic leaders.” This leftward tilt was especially pronounced among groups that are normally seen as base Democratic voters: African Americans, Hispanics, and women.

Since women won decisively in May’s Democratic races, and Democrats are clearly relying on voters of color to take them to victory, these poll numbers deserve attention.

Winning primaries is, of course, only the first step toward getting elected. The left scored some upset victories on May 15. How will these candidates fare in November? To a certain extent, that depends on whether the national party supports them. The DCCC, which had targeted Eastman’s district as a “Red-to-Blue” opportunity, immediately withdrew that designation after Eastman defeated Ashford.

Older voters, who are more likely to resist the “socialism” and “left” labels, typically vote in far greater numbers than other groups. For these voters, progressive Democrats would be well-advised to emphasize their support for expanding Medicare and Social Security. And in order to increase turnout among their base voters, Dems will need to pay more than lip service to social justice and bread-and-butter economic concerns, and to develop an anti-corruption agenda.

Change is a slow process. It will take several election cycles to know whether a new left movement will permanently change Democratic politics, but the progressives who won in May suggest that a meaningful political transformation may be underway.

Richard Eskow is a writer who primarily covers politics and economics. He is also host and managing editor of The Zero Hour With RJ Eskow, a syndicated radio and TV news and opinion program.