In 2012, if the repubs' primary ballot had two options -
"ROMNEY" and "CANDIDATE NOT NAMED ROMNEY" -
I don't think Romney would have won.
1. That is a difficult claim to evaluate, but it would probably depend on the candidate.
2. Even if it were true, it wouldn't necessarily mean that it was Romney's RINOism that was responsible: his hypothetical loss could be caused, for example, by his being the "candidate of change," as McCain called him in a 2008 debate.
3. Let's put that on ice for a moment and use simple intuition to evaluate your previous claim: if a party consciously gives most of its votes and its presidential nomination to a candidate who hiked hundreds of millions in 'fees', backed an assault weapons ban, and implemented Obamacare whilst in power and previously voiced significant support for gay rights, then probably that party doesn't have as many conservatives (remember, we've defined 'conservative' to mean 'Tea Party material, more or less') as you seem to think -- it doesn't matter how many damn candidates were running.
4. You still haven't addressed the evidence from the 2014 primary season: genuine conservatives have almost exclusively lost across the board in over 100 contests -- most of which pitted them against a single establishment opponent. Are these results not indicative of general Republican sentiment and thus also indicative of attitudes toward prospective presidential candidates?
5. The bottom line -- contrary to what your television set is telling you -- is that most Republicans are dispassionate centrists with some views the Faux News types would call liberal, just like the rest of the country. As a random example, most Republicans age 18-50
support gay marriage.
A Ted Cruz-type will never win the party's nomination, let alone end up in the Oval Office. As well, I think previous Republican presidents have been far more RINO than you are willing to admit.