How are Republican candidates doing on the 40(b) requirement?
Rule 40(b) requires that in order for a candidate to be eligible to be voted on at the Republican convention, he must have the support of at least half the delegates from at least 8 states.
Trump has already met this requirement from the following 8 states:
Cruz only as 4 states:
No other candidate has even one state.
In case you are wondering about Rubio, he won less than half of the delegates in Minnesota, and although he won all of Puerto Rico’s 23 delegates, Puerto Rico is a territory and not a state so it doesn’t count.
If the GOPe wishes to stop Trump with anyone but Cruz* (and they hate Cruz as much as they hate Trump), they will have to change rule 40(b) at the convention. Because such a rule change would be for the express purpose of denying the guy with the most votes the nomination. Ironically, the reason why that rule was made in the first place was so the guy with the most votes would get the nomination on the first ballot, because it was believed (with valid reasons) that a drawn-out contested convention led to weakened candidates who would lose to the Democrats.
*This assumes that Cruz qualifies by winning the majority of delegates in four additional states. I think that he could pick up four additional Interior Northwest and Great Plains states. He is most likely to win in: Utah, Montana, Wyoming, Nebraska, South Dakota, North Dakota.