Please ask this of your Christian friends who vote. Especially pose the question to ones who, like some of my family members, say they will vote for Perry, Cain, or Romney because they "have to vote for someone".
Who would Jesus vote for? Do you really think he would vote for the "lesser of two evils"? Isn't that like choosing to commit the lesser of two sins? Do you really think he would want you to vote for the lesser of two evils?
Christians who vote are not obeying his admonition to "Render therefore unto Caesar the things which are Caesar's" and are instead giving Caesar that which does not belong to Caesar: their attention, time, and respect.
Grow up. Withdraw consent.