A quick DuckDuckGo search on "are liberal people more intelligent" or "are left wing people more intelligent" leads to many blogs/articles claiming that they are (same search on the opposite claim ("less" or "conservative") leads mostly to the same links).
What is the scientific consensus on this question ?
EDIT : I am looking mostly for correlation (controlled for confounding variables) but it would be nice to have some insight into possible causes of this correlation (whether one variable causes the other or they are consequences of the same cause). Here is an example of an article claiming that liberals are more intelligent, though the question of whether liberalism and political orientation are correlated does not depend on whether the explanations offered in the article are valid or not. It should also be noted for the sake of irony that its author Satoshi Kanazawa is the exact opposite of a liberal.
EDIT 2: By "liberal/left-wing" I mean stuff like support for the welfare state, economic regulation, civil rights, abortion, minority rights (same sex marriage, etc.), separation of church and state, pacifism, etc... i.e. political positions correlated with one another that are commonly labeled "liberal" or "left-wing". By intelligence I mean mostly IQ and cognitive ability in general.