I remain bearish on Ted Cruz's chance to win the nomination, even if all the other candidates dropped out today, since almost all of his best states are behind him and all of Trump's best states (some of which are winner-take-all) are ahead. But let me put my wet blanket aside for a minute and focus on how Ted Cruz might win.
Ted Cruz does have a path to victory, but it involves a number of sequential events that must happen for it to be plausible. Here, in order, are the things Ted Cruz needs to happen in order to have a chance to defeat Donald Trump and earn the nomination.
1. Ben Carson's voters must completely abandon him. The importance of this to Cruz's success cannot be overstated. Carson basically announced today that he is non-quitting quitting the race, but staying in for those supporters who still want to send him money. Whatever, Carson's campaign is and has been a scam for months. The question is whether his voters will take the hint or continue to vote for him out of some sense of misguided loyalty.
Carson is pulling about 4-5% everywhere, and Ted Cruz desperately needs those votes in a whole host of upcoming contests. If Carson is still in this race come March 15th, this thing is pretty much over for Cruz, for reasons I'll get into later.
Cruz needs to figure out an effective pitch to get these voters to understand that voting for Carson at this point is literally a vote for Trump. Not just in the sense that it is throwing their vote away, but in the sense that Carson's votes, since he won't clear delegate thresholds in any states, will get basically added to the total of the winner, which will be Trump if they don't vote for Cruz.
Cruz's margin against Trump heads up is razor thin; if he doesn't pick up the lion's share of Carson's votes, it does not exist.
2. Ted Cruz must win Kentucky, Kansas and Louisiana on Saturday. Saturday is Ted Cruz's proof of concept. Cruz's argument is that his Super Tuesday finish places him in the best position to unify the non-Trump faction of the party and actually beat Donald Trump. He must show that he can do it in three contests that are tailor made for his strengths. Kentucky, Kansas, and Louisiana all have primary electorates that look almost exactly like Oklahoma's (and Iowa's) - and winning all three will provide Cruz with a PR boost and additional legitimacy that he desperately needs.
Cruz's wins in Oklahoma and Texas were largely overshadowed by all the wins Trump racked up on Super Tuesday. If Cruz wins three out of four against Trump on Saturday, the narrative starts to change a bit. Note that this becomes more difficult if #1 above does not happen.
3. Marco Rubio and John Kasich must not drop out... yet. This seems counter-intuitive, but it's absolutely necessary to Cruz's success. Cruz can't win Florida. In fact, his standing in Florida has cratered in this month's polls (what that says about his chances in the general election is a completely different story), clocking in at 10 and 12% in the two polls taken this month. For as much as Cruz's supporters have taunted Rubio for being behind Trump in Florida, he isn't nearly so far behind in this state as Cruz is. Likewise, it seems unlikely that he will be able to beat Trump in Ohio, especially given that Kasich is absolutely not going to vacate the race before then.
So he must have the next best thing happen, which is for Donald Trump to not get huge delegate hauls on March 15th. The best hope he has for that Kasich to beat a weakened Trump in Ohio and Rubio to beat a weakened Trump in Florida. If Trump doesn't win Texas, Ohio, and Florida, then talk of his inevitability goes out the window and this becomes a genuine dogfight for delegates, with Cruz being clearly in the best position delegate-wise going forward.
Note that this scenario becomes much less unlikely if #1 and #2 don't both happen. If Carson is still around sucking votes from Rubio and Kasich, and if Trump doesn't get his nose bloodied on Saturday, then Trump is going to win both states and the contest will more or less be over.
4. Cruz must persuade Kasich and Rubio to drop out after March 15th. This is maybe the most difficult step of all - somehow convincing a Rubio (who would have just won Florida in this scenario) and Kasich (who would have just won Ohio) t0 drop out of the race. Kasich presumably will be the harder sell, since he is a crazy, egotistical, delusional person with a redass streak a mile wide and who possibly is angling for a cabinet spot in a Trump administration. If Kasich and Rubio win Ohio and Florida, the delegate situation will have been thrown into total chaos and it will be extremely unlikely that any candidate will reach the 1237 threshold. Cruz must somehow prevail upon Kasich and Rubio to either drop out and enthusiastically support him before the convention or at the convention, in order to win. His argument would be a relatively strong one, being the lead delegate-getter who is not named Donald Trump.
It's a difficult path that Ted Cruz has to walk, but it can be done. It starts, first and foremost, with a long, heart-to-wallet conversation between Ted Cruz and Ben Carson.