Reagan won in two landslide elections. Republicans haven't run a conservative since, and haven't had a landslide win since. GHWB squeaked through once (on Reagan's coattails), and lost the second time. Dole lost against what was, at the time, the most corrupt regime in US history. GWB squeaked through twice. McCain lost in a landslide by allowing his staff (borrowed from Romney) attack his conservative running mate. Romney lost in a landslide against what was already proven to be the absolutely most corrupt, anti-American, pro-muslim, evil administration in US history.
More people voted for Romney in 2012 than had voted for McCain in 2008, and he still lost. You cannot blame that on conservatives sitting out the election. You can blame it on many swing voters seeing Romney as Obama-Lite, and sticking with the correctly-labeled liberal.
When Republicans run a conservative, Republicans win.
Jeb Bush is not a conservative. Romney is not a conservative. Christie is not a conservative.
Republicans did the exact same thing against FDR, and lost four times. This recent Cromnibus Bill demonstrates that the GOP-e has learned nothing.
The ideal situation is of course for the GOP to realize that its voter base is conservative. Instead they try to appeal to liberals, as if a liberal will ever vote for a Republican. They keep thinking they have to “reach out” and “compromise”, when experience should tell them it’s principles, not compromise that wins votes. The problem, though, is not just the liberal Republicans, but that often there is no choice in who is nominated for election.