[TomGuy]

The number to win hasn’t changed, I don’t think.

Maybe. Maybe not.

If they adhere to Rule 40, only Trump and Cruz qualify for the ballot, unless Kasich turns into supercandidate and wins 7 states.

So, what becomes of the delegates held by the also-rans? Do they sit on their hands during the first ballot or are they free to vote for whomever they want? If they do sit on their hands, does that reduce the number required for nomination down from 1237?

[jessduntno]

"So, what becomes of the delegates held by the also-rans? Do they sit on their hands during the first ballot or are they free to vote for whomever they want? If they do sit on their hands, does that reduce the number required for nomination down from 1237?"

The delegates for those who have washed out do not sit on their hands, they count to the credit of that candidate. If the 1237 is not reached on the first round, a new round starts. Convention delegates will then start a new vote and vote over and over again until one candidate hits the magic number of 1,237 delegates. Most state parties have their own rules for their own delegates about how many times they are required to vote for the candidate to which they are bound. But by the third ballot, nearly all delegates will be free to vote however they choose. Other national rules will be set by a panel of 112 party officials – two from each state and territory – who will have the power to change the rules just days before the convention, potentially making or breaking the presidential aspirations of candidates who fell short.

It's the rules. It gets complicated because States (as they should, IMO) have their own rules about how they vote.