I have to say that Rubio has the best chance right now, he will get the Bush support for the most part and Kasich also when he finally calls it quits; the Establishment knows this so they will pressure the bottom feeders to quit.
That will put Rubio into a solid 1st or second place in States with Open Primaries and the likely winner in Closed Primary States as well if Cruz stays in.
Trump is pulling about 20 percent of GOP support, he gets to the mid 30’s with Independents and Democrats so he is very strong in Open Primary States; but that means the 45 to 50 percent of GOP support that has been going to Cruz/Rubio and the 20 percent that is scattered among the bottom tier candidates can stop him.
The likely scenario as I see it is this;
- The GOP pressures their Statist guys to quit so Rubio can solidify second place.
- Cruz waits to see if his support can deliver him the win in Closed Primary States, but he likely cannot win those after Rubio consolidates the Establishment wing.
- Cruz then realizes that all he can really do by staying in is to help Trump, he will then have to decide if he thinks Trump would be better than Rubio; given this choice I would bet that Cruz would hold his nose for Rubio before Trump.
So Cruz drops out, most of his support shifts to Rubio, and the Establishment gets their guy Rubio. The GOP Primary structure is nearly impossible to defeat; this outcome was always the most likely even in a year with a near mutiny within the GOP Base.
The only way this Primary structure can be defeated is if Conservatives picked a single horse before voting starts and stayed with them no matter what; this would require far more organization in the Base than is likely to ever form.
Which is why I advocate for forming a Party that does not require the Base having fight their own just as hard as they fight the Democrats.
Rubio does whatever the GOP Leaders tell him to do, that means his campaign in the General will look just like Romney’s; terrified to confront the Democrats and prohibited from making any genuine Conservative arguments or promises.
I am sure that will finally work this time[/sarcasm]