Mail-in ballots and security measures contribute to counting delays in California's close contests, an election expert says, and last-minute voters in the governor's race may slow things down further.

For years, Trump has repeatedly spread falsehoods about "rigged" elections, including in California. Trump’s not alone in his criticism of the pace of California counting ballots, however, he distorted what it means. It’s not a sign of widespread cheating.

It has long been the case that big cities, which have more ballots to count, report results slower than rural counties do. But other shifts have grown more pronounced with the growth of mail voting and with Mr. Trump sowing distrust of mail ballots among Republicans.