Found on Jeff Alworth's blog: Low on the Hog:
liberal - Favoring proposals for reform, open to new ideas for progress, and tolerant of the ideas and behavior of others; broad-minded; favorable to progress or reform, as in political or religious affairs.
partisan (adj) - Devoted to or biased in support of a party, group, or cause: partisan politics.
These two words are neither synonyms nor related. One may be liberal but not particularly partisan (Bill Moyers), partisan but conservative (Harry Reid), or liberal and partisan (Ted Kennedy). The current GOP is principally partisan, not ideologically coherent. George Bush is hated by liberals not because he is conservative (like Ron Paul), but because he is viciously partisan in everything he does. Hillary Clinton is running as a partisan, but not particularly liberal Democrat, while Barack Obama runs as a liberal with less fidelity to the Democratic Party.