Donald Trump has already qualified and I think Cruz has as well or is on the verge and probably will qualify. It is inconceivable that Kasich or anyone else could qualify and therefore the battle will be limited to Cruz and Trump rendering it impossible for the GOP establishment to parachute in a ringer like Paul Ryan.
However, is not entirely clear whether the rule can be freely amended by the rules committee but the weight of opinion seems to indicate that it can be changed by that committee at any time prior to the convention or even during the convention. I further understand that the proposed change of the rule, which we would fear because it would open the way for a GOPe candidate besides Trump or Cruz, must be approved by the delegates as a whole, or their representatives.
Please accept that my understanding in this matter is tentative. It appears that the rules committee is made up of delegates which are chosen by delegates who presumably would be controlled for the most part by Trump and Cruz together. I further understand that the acceptance of a change in the rules would be done by representatives of the delegates who would, again presumably, be controlled by Trump and Cruz with two from each state.
I am subject to correction on this understanding. But if it holds, it would behoove both Trump and Cruz to coordinate opposition to any amendment to the rule of eight.
