In my opinion, this question is utter crap.
What would make you move substantially to the left? In other words what would make you change your personal principles and beliefs? It's not a question of left and right, but what you believe in and how you fit into to the political landscape.
Personally, I think the person who originally came up with this question needs their ass kicked. There is nothing, I repeat, nothing that could make me change my personal beliefs and values. Whether or not I am considered left or right because of those values is irrelevant.
MagiK, I'm assuming you didn't originate this question, and if you did you need your ass whipped.
It's a loaded question. Based upon our previous forays together in the now defunct War Forum, I'm surprised you even considered thinking about an answer to this.