Another interpretation could be that this is a rallying cry for Republicans to find themselves a leader with a brain; no doubt there are smart people buried within the Party. Also, it would be helpful if their spokesperson could be consensus-building, possess integrity, and even the merest inkling of reasonable-ness.
Others: It could also be that a democrat or libertarian owns the vehicle, and is expressing the opinion that Republicans are evil people looking for an evil leader. I feel confident that there are other interpretations for this bumper sticker, but also recognize that I cannot spend the day concocting any more. Back to work I go!