i don't know that i was ever 'liberal' but i think a lot of conservatives would mistake me for one. i don't buy into the left/right paradigm; i am anti-war, vegan, can't stand the war on drugs (even though I don't do them), am atheistic, and have long argued our political system is beyond corrupt. I believe a two party system is destined to fail, that both parties collude, and believe democracy is 'tyranny of the majority'.
But by the same token, I can't stand liberals. I can't stand when people try to legislate morality - be it a primarily religious movement as with prohibition, or the war on drugs, or a 'leftist' one like the war on smoking. I don't understand how anyone can talk about government corruption with half a breath, and then want them in control of more things with the other half.
I'm not libertarian -- I still have reservations regarding pure capitalism that have not been put to rest, though I agree that our federal government is not the solution. However, I can understand the libertarian position, and the end goal is fairly equivalent to mine -- just a slight difference in how to get there.
So... for me, the hardest thing to come around to was the fact that I agreed with a politician. I was so completely distrustful, and it took quite a bit to convince me he's the real deal (though he certainly sounded it from the get go). By comparison, I never believed Obama for a second, and am on record warning my family and friends that voted for him that he would not end the wars, or keep any of his promises. They thought I was crazy then; they think I was prophetic now.
And that's important -- Obama has really, really, pissed off a lot of the left that believed in him. That thought he'd end the wars. End Guantanamo, etc.