Democrats claimed an outright majority of votes in California’s 49th, which makes them clear favorites to win the district in the general election. In five other districts, the Democrats received between 45 percent and 48 percent of the major party vote, setting up races that could be characterized as tossups or leaning Republican, just as they’re currently rated by the Cook Political Report.

Image Mike Levin and his wife, Chrissy, on Tuesday night. He will most likely be the Democratic candidate in California's 49th District, which appears to be the Democrats' best chance to flip a district in the state in November. Credit... Hilary Swift for The New York Times

There was one notable outlier: California’s 21st, represented by the Republican David Valadao. Mr. Valadao currently holds 64 percent of the vote, a tally that, historically, would make him all but a lock to win the general election.

It would probably be a mistake to completely write off a competitive race in the 21st District, where Hillary Clinton won by double digits. This is the least-educated congressional district in the country, and Hispanic voters make up a majority of the electorate. Turnout was extremely low. Absentee ballot data indicates that the turnout was particularly weak among Democrats and Hispanic voters. According to Political Data Inc., Democrats had just a three-point edge in returned ballots, compared with their 19-point advantage among those who received a ballot in the mail. Similarly, Latinos made up 38 percent of returns, compared with 60 percent of the mailed ballots.

The low Hispanic turnout in the Central Valley dragged down Democrats across the board, like the incumbent Democratic congressman Jim Costa in the neighboring 16th District (who claimed 53 percent of the vote, with a stronger Democratic turnout), and the Democratic Assemblyman Rudy Salas, who only won 48 percent of the vote. Maybe Democrats will make more gains here in the late balloting than elsewhere.

Democrats, obviously, can’t feel great about low Hispanic turnout. But of the reasons to fall well short of expectations in a district, it’s probably one of the least discouraging ones. It’s not likely to repeat itself elsewhere, and Democrats can reasonably hope for a stronger turnout in the general election. After all, Mr. Salas and Mr. Costa presumably remain heavy favorites in the general election, despite their close contests. If that’s true, Mr. Valadao should still be considered vulnerable.

But Mr. Valadao’s wide margin is probably large enough to merit a modest, tentative reassessment. No congressional candidate has lost a general election in Washington (since 1990) or California while receiving such a large share of the major party vote in a top-two primary. The demographic peculiarities of the 21st District make it easier to imagine weird things happening here, but at the moment it seems like a stretch to characterize this race as merely “leaning Republican.”