Political analysts suggest that young voters in California, who registered at a frenetic pace in the last weeks before the June 7 primary, failed to turn out to vote for Bernie Sanders as expected.

Overall turnout missed expectations, and Hillary Clinton outperformed her poll numbers, winning by a landslide when polls indicated that the race should have been a nail-biter. Young voters were 25% of those registered to vote by mail, but only 10% of those who did so.

Bay Area public radio station KQED reported:

One major factor in that lower-than-anticipated turnout: For the most part, an analysis of vote-by-mail ballots suggests, those younger voters simply didn’t participate. Paul Mitchell, vice president of Sacramento-based Political Data Inc., noted Wednesday that people under 35 made up more than half of 2.3 million new voters who registered before the primary, indicating an enthusiasm for the contest. And he says those younger voters told pollsters they would cast ballots. “But then when they got the ballot with the 34 candidates for Senate, and who’s my congressman, and what’s this ballot proposition, and where do I keep a stamp and all these things … they kind of fell off and they didn’t participate in the same numbers,” Mitchell said.

Hillary Clinton dominated among older Democratic voters. And some analysts suggest that polls may have appeared closer than they were because older voters were less likely to reveal their preferences to pollsters. Mark DiCamillo of the Field poll told the San Jose Mercury News “that among participants who had already voted, it was mostly older ones — those more likely to vote for Clinton — who refused to disclose their choice to pollsters. That, he said, likely resulted in him underestimating her margin of victory.”

Polls may also have under-sampled Latino voters because of language barriers, missing Clinton’s larger-than-expected support in that community as well.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. His new e-book, Leadership Secrets of the Kings and Prophets: What the Bible’s Struggles Teach Us About Today, is on sale through Amazon Kindle Direct. Follow him on Twitter at @joelpollak.