I understand why polls like this can matter to politicians, but they are really, really, really bad for getting at people's actual beliefs. Republicans have been very good at associating the word "conservative" with anti tax and small government (as well as some social issues). Republicans have also been successful at having the word "liberal" associated with high tax and wasteful spending.
The fact is that if you go through policy and public preference, "liberal" kicks "conservative"'s ass. People like social security. People like medicare. People like education and student grants. People like having clean places to live: clean air to breathe and clean water to drink and for recreation. People like the idea of leaving a better world for their children.
On the pro-conservative side, people don't like taxes. People like the military.
People don't like "big government" either when that is the label, but in fact what people don't like is "bad government". Anyone who relies on self-identify polling to determine whether the public is "liberal" or "conservative" is shockingly stupid.