Sometimes the pundits get an election wrong. It happens.

But it isn’t often that they admit it before the votes are counted.

Welcome to the June 7 primary. Months ago, we considered the usual statistics about low voter turnout. People just don’t seem to care, we said. And we assumed that this June primary would be Exhibit A for a lack of civic interest in elections.

And then two things happened: Bernie Sanders and Donald Trump. Problem solved.

Since the first of the year, the state has registered nearly 2 million new voters. And the number is growing. Last month, California Secretary of State Alex Padilla said that in a 48-hour period, May 16-17, California registered almost 200,000 voters online. As Paul Mitchell of Political Data Inc. wrote, it was “an astounding figure,” almost as high as the total online registration for the past two years.

What’s more, 45 percent of that group was under 30.

“Obviously, this is being viewed as an historic election,” says Mark Baldassare, CEO of the non-partisan Public Policy Institute of California. “The election is now being viewed as sort of, ‘What is our future going to look like?’”

OK, you have our attention. Now, what does that mean?

We have a simple answer: Nobody knows.

San Francisco political consultant David Latterman can only shrug.

“We don’t totally know how this is going to shake out,” he said. “It’s hard to predict what will happen with these new voters.”

And, yet, it looks so simple and clear cut. For starters, San Francisco has experienced the same surge in voter registration as the rest of the state. Latterman says there are roughly 50,000 new voters, 58 to 60 percent of whom are Democrats.

So, conventional wisdom would predict a banner election for progressive causes. Because, of course, the kind of young, Democratic voters who are backing Sanders are extremely liberal.

Not so fast. For starters, the under 35-year-olds may be registered, but will they vote?

‘Cathartic rush’

Mindy Romero of the UC Davis California Civic Engagement Project reminds us that historically, young voters have not been big factors, especially in primaries.

“In the June 2012 primary,” she says, “the turnout rate for young voters was only 5.2 percent (of those registered). In the 2014 primary it was 3.1 percent.”

And there’s another factor. Although much has been made of the Millennials supporting Sanders, they’re anything but straight-ticket party voters. Romero says the pool of “NPP” voters (no party preference) is increasing dramatically in California, and “it is young people who are driving that.”

As a side note, Mitchell says that “68 percent of the young voters registered as vote by mail.” That’s important because, although the Democratic Party allows independent voters to vote in the presidential primary (the Republican Party does not), NPP voters have to request a special ballot. And most haven’t. (Although they can still request them at polling places.) If they can’t vote for Bernie, they may not bother to mail in a ballot.

“I think that could be a big story coming out of the election,” Mitchell says. “Yes, we had this big, statewide cathartic rush to register to vote, but when election day came, was it just the same likely voters (whiter, older) who participated?”

And, just to add to the confusion, one more thought. The last time the young electorate was galvanized like this was the 2008 presidential election of Barack Obama. However, Latterman says the support didn’t translate to extremely liberal causes.

“They voted for Obama,” he said. “But down the ticket they voted pretty much like the rest of Democrats. We’re seeing that now. Millennials are pro-Bernie, but they are also pro-housing and pro-transportation. People are expecting these dyed-in-the-wool progressives, but that isn’t necessarily true.”

In San Francisco we have the perfect test case — the state Senate race between moderate Scott Wiener and progressive Jane Kim. The original theory was that Kim only had to make a representative showing in the primary and could save the big push for the November general election.

From words to action

But now the thinking is that when polling showed Kim trailing by double digits — the race has narrowed since — she pulled out all the stops. She needs to make this close, or she won’t be able to attract funding for November.

As we’ve seen, Kim is cozying up to Sanders, who endorsed her, with the hope that motivated Millennials will drive up her results.

But will they turn out? And if they do, will they be progressive or pragmatic voters? All we know is that they’re interested.

“Young people never talk about a primary election,” Romero said. “Now I have young people on this campus talking about it every day.”

Are they just talk?

C.W. Nevius is a San Francisco Chronicle columnist. His column appears Tuesday, Thursday and Saturday. Email: cwnevius@sfchronicle.com Twitter: cwnevius