Donald Trump is the Republican nominee for President. This has caused a giant crisis of confidence among Republicans who are committed to denying that Trump represents the Party which voted, by overwhelming margins, for him to be their standard-bearer (as Scott Lemieux observes, the best part of this narrative is when it claims that folks like John McCain and Lindsey Graham are "leading Republicans", as opposed to, say, Donald Trump). And that has created a small cottage industry of figuring out how to blame Democrats for Trump's rise. They cried wolf, Jonah Goldberg wails! Indeed they did, says David Graham. How could Republicans take the charge that Trump was a sui generis threat to American's democratic character, when Democrats always are calling Republican politicians terrible, horrible, no good very bad candidates for higher office?
If this complaint strikes you as pathetic, that's because it is. Obviously, Democrats are generally not going to like Republican nominees for higher office (if we did, either we'd be Republicans or they'd be Democrats). Republicans are responsible for their own nominee, if their nominee reflects poorly upon them, that says nothing more than that they are who we thought they were.
But the real question is why Republicans are supposedly entitled to rely on Democrats to keep them in check? We are not their keeper, after all. Why didn't their own self-generated political principles put the breaks on Trump? The answer seems to be that Republicans at this point, by their own admission, lack any self-generated political principles. As one commentator astutely put it at the end of Obama's first term: "[T]oday’s conservatism is the opposite of what liberals want today: updated daily." The entire conservative movement today is one large exercise in ressentiment against urban coastal multicultural liberal elites, entirely reactive, creating nothing of its own. Of course it relied on Democrats to behave in such a way as to not "create a Trump"; Democrats -- indirectly -- create everything the contemporary Republican Party "stands" for.
Theirs is, as Nietzsche would put it, a Party beset by sickness. And while it's not the case that only a Party that sick could produce a Trump, it is the case that only a Party that sick could blame its opposition for forcing them into it.