The final few delegates aren’t easy for Mr. Trump. He has a few options:

■ Win Indiana. It would probably be worth at least 42 delegates and as many as 57, enough to put him over the top if everything went his way. There’s reason to think Indiana is promising for Mr. Cruz, but the state is something of a mystery. There hasn’t been a single poll there this year.

■ Squeeze out every delegate he can from the coasts. Mr. Trump could claim additional delegates from California or the Northeast beyond what was assumed above. A near sweep of the Northeast and California could get him over the top, even without any help from Indiana.

■ An upset. Mr. Trump could squeak out a win in a state where he’s thought to be an underdog, like Montana. It’s not likely — that’s why he’s an underdog. But it’s not impossible.

■ Win Pennsylvania’s unpledged delegates. If all else fails, Mr. Trump could still win it at the convention with the unbound delegates from Pennsylvania. Here, voters directly elect 54 of the 71 delegates, but they aren’t bound to any candidate.