Some day, maybe soon, conservative sentiment will be so strong in the electorate that it will sweep a conservative to the Republican nomination and the White House, but if conservatives haven't been able to win the nomination since Reagan, could that be a sign that conservative sentiment in the country isn't as strong as some people think, and may not be strong enough in itself to carry any of the conservatives who've run to the nomination, let alone the presidency?
It could be that 60% of the country is conservative enough about some things to call themselves conservatives (Gallup says it's less than that, with almost as many people calling themselves moderates as conservatives, and we know how a lot of those moderates vote), but that doesn't mean that those voters are conservative about everything and would respond to a candidate who is conservative in ways that they aren't.
With people who say they are fiscally or economically conservative but socially liberal and those who are socially conservative but think Republicans are for the rich guys, it can be hard for Republicans or conservatives to get to 50%.
The trouble is the Republicans are no longer conservative in any sense of the word. They sold out on taxes and spending, they sold out on abortion, they sold out on immigration, they are in the process of selling out to the gay mafia and joining their sordid and tyrannical ranks, they sold out on obamacare. They are not socially or fiscally as they spend like drunken sailors with 6 months back pay everyday. About the only think they haven’t sold out is the 2nd Amendment-—yet, mainly because the NRA would tear them a new one and they know it. So they no longer offer a viable alternative to liberalism, just a cheaper version of it.