If this holds, the delegate math is a little different than what you might have read last week here or elsewhere. That’s because my analysis and that of others included only pledged delegates; the 54 unpledged delegates were held out of Mr. Trump’s path to 1,237.

If he has indeed moved many of those delegates off the sideline and into his territory, it obviates the necessity for him to win Indiana, which is worth 57 delegates (30 delegates to the statewide winner and three delegates to the winner of each of nine congressional districts). He would still need a comfortable victory in California — enough to win about 130 of the state’s 172 delegates in the event of a loss in Indiana. He could bring that figure as low as 115 with good outcomes in West Virginia, Oregon, Washington and New Mexico, or with a few additional districts in Indiana.

The 130-delegate target in California is achievable. The state awards its delegates on a winner-take-all basis statewide and by congressional district, so Mr. Trump would need an overall victory (13 delegates) and wins in about 40 of the state’s 53 congressional districts to pull it off. Even a modest popular vote victory could do the trick. In 2008, John McCain won 48 of California’s 53 congressional districts with a 7.5-point margin of victory in the popular vote. And Mr. Trump won every congressional district Tuesday night in the Northeast.

Mr. Trump leads in all of the most recent California polls; he had an eye-popping 49 percent of the vote in the most recent Fox News and CBS News/YouGov surveys.