Here's a great article on Barack Obama’s rhetorical strategy of redefining liberal values as mainstream values, and refusing to be put in the liberal “box”. The article points out that not only is this a successful way to appeal to voters across the ideological spectrum, but it is also a powerful way to advance liberal issues and values.

But in the heart of a Democratic primary -- when bashing Republicans and acting partisan is in anyone's best interest -- Obama continues to push our values out to the majority. It's a brilliant move: Democratic goals and values aren't just liberal. They are American goals and values: ethical government, availability of health care and college, a common sense foriegn policy, and more.
Listen to his speeches. He constantly talks about his core liberal philosophy in a way that's appealing to non-liberals.

By promoting liberal positions on issues like those mentioned above (and I would add nuclear arms control, clean energy, and other issues to that list) as “American” values, rather than “liberal” values, Obama reframes the debate and presents these issues in a way that is inviting to those who don’t think of themselves as “liberals”. This approach has helped him win many supporters from more moderate and conservative backgrounds without having to triangulate his actual positions on the issues. Very cool.